Anti-corruption prosecutors asked Romanian President Traian Basescu on Tuesday to authorise a criminal investigation against Justice Minister Tudor Chiuariu for alleged graft-related crimes.
Chiuariu, a member of the ruling Liberal Party, said the prosecutors' request was "silly revenge". He has made no public comment on the alleged, but unspecified, crimes.
Prosecutors also asked Basescu to approve an inquiry into the activities of former Communications Minister Zsolt Nagy in the same case.
Nagy, a member of the ethnic Hungarian party, a minor ruling coalition partner, was suspended from his post in June pending another criminal investigation related to privatisation plans in the telecoms sector.
He has denied any wrongdoing in both cases.
Investigators need presidential authorisation to launch criminal inquiries against acting and former cabinet members. A special presidential committee will meet in the coming days to analyse the request.
"The chief anti-corruption prosecutor has asked Romania's president to order the criminal investigation of Zsolt Nagy and ... Tudor Chiuariu for committing crimes assimilated to corruption crimes, namely power abuse against public interest," a statement from the prosecutors said.
A spokeswoman with the graft prosecuting office said further details could not be revealed until the presidential committee had reached a decision.
Earlier this month, prosecutors said in a statement that they were investigating dealings between the state-owned postal services company and two private firms, including legal papers approved by the communications and justice ministries.
Chiuariu took over the justice ministry in an April government reshuffle from Monica Macovei, who is seen as the architect of Romania's judicial reforms and has been praised for her work by the European Union.
Earlier this year he asked the magistrates' watchdog to sack a top graft prosecutor on the ground that he was ineffective, a move civil rights groups said was an attack on prosecutors' independence.
The European Union, which is monitoring Bucharest's progress in carrying out reforms since it joined the bloc in January, has said Romania must step up the fight against widespread fraud.
The Bucharest government has repeatedly said it is working hard to combat corruption, but Transparency International ranks Romania as the EU's most graft-prone country.