A resistance group says a Russian ammunition depot was destroyed and shells were detonated in Mariupol overnight into Saturday, according to Petro Andriushchenko, an adviser to the city's elected Ukrainian mayor.

Andriushchenko, who is not in Mariupol, said that several pieces of Russian armor had been destroyed and 50 Russian troops had been killed or badly injured in the strikes.

Social media accounts allege further heavy explosions have been heard in the Russian-occupied city.

CNN cannot independently confirm Andriushchenko's claims.

For the last few days, social media accounts have published nighttime video purportedly from Mariupol that has included the sound of heavy detonations.

There are heavy concentrations of Russian forces and equipment in the city.

US President Joe Biden dismissed China's call for peace talks on the war in Ukraine, suggesting its implementation would only benefit Russia.

"If Putin is applauding it, so how could it be any good?" Biden said in an interview with ABC News on Friday. "I’m not being facetious. I’m being deadly earnest."

"I've seen nothing in the plan that would indicate that there is something that would be beneficial to anyone other than Russia if the Chinese plan were followed," Biden said. 

Beyond his criticism of the 12-point Chinese proposal, Biden outright rejected the notion of China negotiating peace in the war.

"The idea that China is going to be negotiating the outcome of a war that is a totally unjust war for Ukraine is just not rational," Biden said.

Biden also weighed in on the possibility of China providing lethal weapons to Russia, which US officials have warned of in recent days.

Biden declined to outline the consequences of China arming Russia, but suggested Beijing would face the same "severe sanctions" as any other government or entity that has supplied weapons to Russia.

Some background: The US has intelligence that the Chinese government is considering providing Russia with drones and ammunition for use in the war in Ukraine, three sources familiar with the intelligence told CNN.

It does not appear that Beijing has made a final decision yet, the sources said, but negotiations between Russia and China about the price and scope of the equipment are ongoing.

China's Foreign Ministry said Friday that the country takes a "responsible approach" to military exports and does not provide arms sales to conflict areas. The statement comes a day after a German media outlet claimed Beijing is negotiating with Moscow to supply drones.