The United Nations on Tuesday threatened to end its political mission in Nepal unless the warring political parties make a greater effort to end the country's deadlock.

UN Secretary General Ban Ki-moon a withdrawal would be considered if Nepal did not quickly form a government and hold talks on the UN mission.

"I will propose alternative measures to the (Security) Council, including the possible termination of UNMIN's mandate," Ban said in a report to the Security Council.

"I call on the parties to invest greater effort in serious and sustained political dialogue," the UN secretary general added.

The Security Council met hours after Nepal's parliament failed for the seventh time to elect a new prime minister, prolonging a stalemate that has threatened the country's fragile peace process.

There has been no government since June 30, when Madhav Kumar Nepal stood down as prime minister, under pressure from the opposition Maoist party. Since then the rival sides have failed to agree the shape of a new administration.

The UN Mission in Nepal (UNMIN) was set up after a civil war ended in 2006, with a temporary mandate to monitor the Maoist and national armies and assist with the peace process. It has repeatedly expressed frustration at the slow pace of progress.

The UN chief said again that there has been "no substantive progress" on the future of the national and Maoist armies and drafting a constitution.

"The major parties are preoccupied by profound internal fissures and the question of power-sharing," he said, also complaining about attacks on the UN mission by Nepal's rival parties.