Malaysia's prime minister said Monday he will seek to cancel multibillion-dollar Chinese-backed infrastructure projects that were signed by his predecessor as his government works to dig itself out of debt, and he blasted Myanmar's treatment of Rohingya Muslims as "grossly unjust."

Mahathir will visit China on a five-day trip starting from this Friday, China's Foreign Ministry said Monday, the leader's first visit there since returning to power in an electoral upset three months ago.

Mahathir, 93, will meet Chinese Premier Li Keqiang as well as President Xi Jinping.

Mahathir, who came to power in May following a stunning election defeat for then prime minister Najib Razak, is reviewing major projects signed by the former government, saying many of them do not make financial sense for Malaysia.

In a wide-ranging interview with The Associated Press, Mahathir said he wants to maintain good relations with China and welcomes its investment, so long as the projects benefit Malaysia.

But he took his toughest stance yet on Chinese-backed energy pipelines and a rail project along peninsular Malaysia's eastern coast that were struck by his predecessor Najib. The former premier faces trial on multiple charges related to the alleged multibillion-dollar looting of the 1MDB state investment fund. He denies wrongdoing.

"We don't think we need those two projects. We don't think they are viable. So if we can, we would like to just drop the projects," he said from his office in the administrative center of Putrajaya.

During his time in power, Najib drew Malaysia closer to China, which sees the multiethnic Southeast Asian country as a key part of its ambitious One Belt, One Road global trade initiative. The former prime minister reached deals for the 688-kilometer (430-mile) East Coast Rail Link and the two gas pipelines in 2016.

Malaysia's new government has already suspended work on the projects, being built by Chinese state-backed companies, and called for drastic cuts in their ballooning cost, which it estimates at more than $22 billion. Some of that money has already been paid and could be difficult to recoup.

If scrapping the projects altogether isn't doable, Malaysia will need to at least put them on hold until the future, Mahathir said.

Mahathir also urged China to respect the free movement of ships throughout the South China Sea. China and multiple Southeast Asian nations including Malaysia have competing claims on islands and reefs in the sea — along with the rich fishing grounds and potential fossil fuel deposits around them.

China claims much of the sea as its own and has built up several man-made islands equipped them with runways, hangers, radar and missile stations to bolster its claim. It has accused the U.S., which routinely deploys aircraft carriers, other warships and planes to the sea, of meddling in a purely Asian dispute. Chinese ships also patrol the sea.

"We are all for ships, even warships, passing through, but not stationed here," Mahathir said. "It is a warning to everyone. Don't create tension unnecessarily."

Mahathir was scathing in his criticism of Myanmar for its treatment of the Rohingya Muslim minority group.

"It is grossly unjust to do what they have done, killing people, mass murder, that's not the way civilized nations behave," he said.

Predominantly Muslim Malaysia has strongly supported the Rohingya, a persecuted minority in Myanmar who have fled by the hundreds of thousands to neighboring Bangladesh after a crackdown last year that has been called ethnic cleansing. Malaysia has said the displacement of Rohingya is no longer a domestic issue for Myanmar, in a rare departure from ASEAN's non-interference policy in each other's affairs.

Mahathir added that he was "very disappointed" in Myanmar leader Aung San Suu Kyi's failure to halt the oppression.

"Obviously she appears to be with the government of the day on how they treat the Rohingyas. It's a question of justice and human rights. You can't do that," he said.

A longtime champion of Palestine, Mahathir pushed back against accusations that his comments on Israel are anti-Semitic, saying that "we should be able to criticize everybody" while assailing laws denying the scale of the Holocaust.

Mahathir's criticism of Western leaders has extended to President Donald Trump, whom he described as an "erratic man" during an AP interview last year. His return to office hasn't tempered his opinion.

"So far he has not indicated that I should change my views," he said of Trump on Monday. "He changes his mind within 24 hours. I mean it is difficult to deal with any person whose mind is not made up."

Still, Malaysia would continue to welcome American investment, particularly in high-tech sectors, he said, as he promised tax breaks and other incentives.