BEIJING — The Chinese authorities have detained six anticorruption activists in recent days, expanding their crackdown on a citizen-led campaign that, on the surface at least, would appear to dovetail with the new leadership’s war on official graft.

The detained activists, who include seasoned dissidents and a prominent rights lawyer, had been demanding that senior Communist Party officials publicly disclose their personal wealth, according to lawyers and rights advocates.

The campaign, started late last year with a petition drive that garnered thousands of signatures, has tried to piggyback on a pledge by President Xi Jinping to clean up the endemic corruption he says poses an existential threat to the ruling Communist Party.

In widely quoted comments published in January, Mr. Xi promised to take down “tigers and flies” — a reference to high-ranking officials and middling bureaucrats — but the public clamor for mandatory asset disclosure has so far received a tepid response from Chinese leaders.