The United Nations urged all parties in Pakistan to refrain from resorting to violence in the aftermath of the arrest of former Prime Minister Imran Khan.
"The secretary-general takes note of the ongoing protests that have erupted following the arrest of former Prime Minister Imran Khan yesterday in Islamabad and calls for all parties to refrain from violence. He stresses the need to respect the right to peaceful assembly," said a statement by Farhan Haq, deputy spokesperson for Secretary-General Antonio Guterres.
"The secretary-general urges the authorities to respect due process and the rule of law in proceedings brought against former Prime Minister Khan," the statement added.
At least six people were killed and several others injured after protests broke out across Pakistan against the arrest of Khan on Tuesday.
Khan was arrested on May 9 in connection with alleged corruption involving the Al-Qadir University Trust.
It is alleged that the cricketer-turned-politician and his wife, Bushra Bibi, received billions of rupees and a large piece of costly land to build the educational institution in return for releasing an amount of £190 million ($239 million) to a property tycoon in 2020.
The amount was identified and returned to the country by the U.K.'s National Crime Agency (NCA), following a settlement with real estate tycoon Malik Riaz in 2019.
The National Accountability Bureau, Pakistan's anti-corruption body, alleges that Khan's PTI government struck a deal with Riaz that caused a loss of more than $239 million to the national exchequer, in a quid pro quo arrangement with the businessman.
Khan and his party leaders, however, deny the allegations.
Khan was arrested on Tuesday during a routine hearing in the capital Islamabad and whisked away to an unknown location overnight before appearing behind closed doors in a specially convened court at police headquarters.
The drama follows months of political crisis during which Khan, who was ousted in April last year, has waged an unprecedented campaign against the country's powerful military.
"If they think that the arrest of Imran Khan will demoralise us, then they are hugely mistaken," said Niaz Ali in Peshawar, where several monuments and government buildings have been torched.
"We stand with Imran Khan and will support him till death."
Ali Bukhari, a lawyer for Khan, told AFP by phone that the court had approved eight days of physical remand of Khan demanded by the country's top graft agency.
Afzal Marwat, another of Khan's lawyers, earlier said Khan was in "good spirits" but had complained of being hit on the back of the head and leg by paramilitary forces who arrested him.
The former cricketing superstar, who remains wildly popular, has previously said the dozens of cases brought against him are part of an effort by the struggling government and military establishment to prevent him from returning to power.
His arrest has brought thousands of his supporters to the streets in cities across the country, where police have attempted to quell crowds with tear gas.
At least six people have died in protest-related incidents, police and hospitals reported, including one person who died from smoke inhalation after a multi-storey building was set on fire in Lahore.
Russia urges calm in Pakistan
Russia also called on all parties in Pakistan to resolve their difference through peaceful means.
Speaking at a press briefing in Moscow, Foreign Ministry spokeswoman Maria Zakharova said Russia is "closely following" the events surrounding the arrest of former Pakistani Prime Minister Imran Khan.
"We call on all parties to resolve differences by peaceful means, we expect that mass protest actions in Pakistani cities will take place without serious clashes, the situation in the country will soon normalize," Zakharova said.