An ammunition depot in Russian-annexed Crimea exploded on Tuesday, injuring two people and disrupting railway traffic between the peninsula and the rest of southern Ukraine and Russia, the region's top Russian-backed official said.

Sergei Aksyonov, the top Russian official in Crimea, told state TV that he did not want to talk about what may have caused the explosions, something he said was being looked into.

He said around 2,000 local people had been evacuated from the nearest village beyond a 5-kilometer (3.1-mile) perimeter.

Russia has used Crimea to reinforce its troops fighting in what it calls a "special military operation" in Ukraine with military hardware. The damage reported to the peninsula's rail network on Tuesday could disrupt that process.

Russia's RIA news agency said seven passenger trains had been delayed and that rail traffic on part of the line in northern Crimea had been suspended. Aksyonov said bus services would be provided to allow people to continue their journey.

The Russian Defense Ministry said there were no casualties from the blasts in the northern Crimean village of Mayskoye, state-owned news agency RIA reported. The agency also reported a fire at a transformer substation 20 kilometers away.

The ministry also said a military warehouse near the town of Dzhankoi in northern Crimea had been damaged by sabotage, Russian state-owned news agency RIA reported.

Earlier on Tuesday, Crimean officials said there had been a major fire at an ammunition depot in the area. State-owned news agency TASS cited the Defense Ministry as saying that civilian infrastructure, including an electricity supply station had been damaged as a result of the "sabotage."

The Crimean Peninsula on the Black Sea, which Russia seized and annexed from Ukraine in 2014 in a move not recognized by most countries, is the base of Russia's Black Sea Fleet and popular in the summer as a holiday resort.

Last week, blasts at a military air base in the city of Novofedorivka, on Crimea's western coast, caused extensive damage and destroyed several Russian warplanes. Moscow called that an accident, though simultaneous blasts at several parts of the base had left craters visible from space.

Ukraine has not officially confirmed or denied responsibility for explosions in Crimea, though its officials have openly cheered incidents in territory that, until last week, appeared safe in Moscow's grip beyond the range of attack.

"A reminder: Crimea of normal country is about the Black Sea, mountains, recreation and tourism, but Crimea occupied by Russians is about warehouses explosions and high risk of death for invaders and thieves," Ukrainian presidential advisor Mykhailo Podolyak tweeted after the reports from Mayskoye.

A British Defense Ministry intelligence update claimed that in the waters off Crimea Russia’s Black Sea Fleet surface vessels "continue to pursue an extremely defensive posture," with boats barely venturing out of sight of the coastline.

Russia already lost its flagship Moskva in the Black Sea and last month the Ukrainian military retook the strategic Snake Island outpost off Ukraine’s southwestern coast vital for guaranteeing sea lanes out of Odessa, Ukraine’s biggest port.

The Russian fleet’s "limited effectiveness undermines Russia’s overall invasion strategy," the British statement said. "This means Ukraine can divert resources to press Russian ground forces elsewhere."

Kyiv aims to disrupt Russian supply lines ahead of a planned Ukrainian counter-attack. Mayskoye is on the main railway line linking Crimea with Russia and is used to supply Russian forces in southern Ukraine.

Like the air base, it is out of the range of the main rockets Western countries acknowledge providing Ukraine so far, suggesting that if the explosions were some form of attack, Kyiv has acquired the capability to strike deeper into Russian territory.

With the war raging since Feb. 24, attention has also focused in recent days on shelling in the vicinity of the Zaporizhzhia nuclear plant in southern Ukraine. Both sides have blamed each other for risks to Europe's largest nuclear facility, which Russia has seized though Ukrainian technicians operate it.

Ukrainian President Volodymyr Zelenskyy has accused Russia of using the site as a shield for attacks and risking a nuclear catastrophe. He wants new sanctions on Moscow's nuclear sector.

Russian officials say it is their enemies who are shelling.

'No need to use nuke'

Russia has "no need" to use nuclear weapons in Ukraine, its defense minister said on Tuesday, describing media speculation that Moscow might deploy nuclear or chemical weapons in the conflict as "absolute lies."

"From a military point of view, there is no need to use nuclear weapons in Ukraine to achieve the set goals. The main purpose of Russian nuclear weapons is to deter a nuclear attack," Russian Defense Minister Sergei Shoigu said during a speech at an international security conference in Moscow.

"The media are spreading speculation about the alleged use of Russian tactical nuclear weapons in the course of the special military operation, or about the readiness to use chemical weapons. All these informational attacks are absolute lies."

Shoigu also alleged that Ukrainian military operations were being planned by the United States and Britain, and that NATO had increased its troop deployment in Eastern and Central Europe "several times over."

Referring to the New START Treaty to control U.S. and Russian nuclear arms, Shoigu said talks to extend the treaty were "a two-way street," and the situation around it was "difficult."

"A difficult situation is also developing with regard to the Treaty on the Limitation of Strategic Offensive Arms. The agreement remains in force until 2026," Shoigu added.

"On the Russian side, obligations are being fulfilled, the declared levels of carriers and warheads are maintained within the established limits."

The nearly six-month conflict has caused millions to flee, killed thousands, and deepened a geopolitical rift between Moscow and the West.

Russia calls its invasion a "special military operation" to demilitarise its neighbor, protect Russian-speaking communities and push back against the NATO military alliance's expansion.

Ukraine and Western backers accuse Russian President Vladimir Putin of waging an imperial-style war of conquest.

Putin accused the United States of trying to "drag out" conflict in Ukraine by supporting the Zelenskyy government. Washington also wanted to extend a "NATO-like system" into the Asia-Pacific region after "a thoroughly planned provocation" with U.S. House of Representatives Speaker Nancy Pelosi's visit to Chinese-claimed Taiwan this month, Putin told a conference.

On the battlefield, the sides reported no major changes to positions.

Ukraine reported continued Russian shelling and rocket attacks in the Donbass eastern area, and success in repelling attempted Russian advances near the Lysychansk oil refinery in the Luhansk region of Donbass.