Malaysia's anti-graft agency has frozen bank accounts of the political party once led by former premier Najib Razak as part of its probe into beleaguered state fund 1Malaysia Development Bhd, media reported on Friday.

Najib's United Malays National Organisation (UMNO) is believed to have received funds from 1MDB, which is the subject of money laundering probes in at least six countries.

Malaysia reopened investigations into 1MDB last month after a shock win by Mahathir Mohamad's alliance, which defeated an UMNO-led coalition that had governed the country for over 60 years until last month.