Ruangkrai Leekitwattana on Monday cited Articles 78 and 79 of the NACC law as allowing such action to be taken.
He also presented to the NACC two photographs showing Prawit, who is deputy prime minister and defence mister, wearing an expensive watch.
Prawit should disclose his assets straightforwardly rather than having the media expose them, Ruangkrai said.
The Pheu Thai lawyer also said the NACC had scrutinised former PM Yingluck Shinawatra when she had been seen wearing a Bt2.5-million watch, as well as another 500 cases involving political office holders.
It should therefore be able to undertake similar scrutiny in the case involving Prawit, he insisted.