Australian deputy Prime Minister Warren Truss announces retirement

Australia's deputy prime minister announced his retirement today, with the prime minister likely to announce a cabinet reshuffle before elections due this year.

Deputy Prime Minister Warren Truss, who is the minister for regional development and infrastructure, told Parliament he will retire at the next elections.

Truss also immediately resigned as leader of The Nationals party, the government's junior coalition partner. His replacement as party leader will be decided by his colleagues later today and the new leader will automatically become the deputy prime minister.

Trade and Investment Minister Andrew Robb announced on Wednesday that he too will leave politics at the next elections.

Prime Minister Malcolm Turnbull made a major overhaul of the conservative government's cabinet in September after he replaced Prime minister Tony Abbott in a leadership ballot of lawmakers in the ruling Liberal Party.

He has yet to name a replacement for Minister for Cities and the Built Environment Jamie Briggs, who resigned in December over a drunken incident with a female public servant in a Hong Kong bar.

The futures of two ministers, Stuart Robert and Mal Brough, remain in doubt due to ongoing investigations. Turnbull's department is investigating whether Robert, minister for veterans' affairs, breached ministerial standards when he flew to China in 20014 to help a friend and Liberal Party donor secure a mining deal with the Chinese.

Brough stood aside as special minister of state and minister for defense materiel and science in December while police investigate allegations that he illegally accessed the diary of a former House of Representatives speaker.

Truss is expected to be replaced as Nationals leader and deputy prime minister by Agriculture Minister Barnaby Joyce, who is currently the party deputy.