Three political parties that brought down East Timor's minority government say they will campaign under one umbrella for new elections due in May.

The parties in the grouping, which calls itself the Alliance for Change and Progress, on Friday announced their official lists of candidates.

East Timor's parliament was dissolved in January after a minority government formed last year was unable to get its policy program and budget through parliament.

The alliance includes the National Congress for Timorese Reconstruction party, led by former prime minister and independence hero Xanana Gusmao, and two smaller parties that won seats for the first time last year.

Fretilin and the Democrats, which made up the minority government, said they will campaign separately but could renew their coalition if they win enough votes.

Gusmao said the political developments of the past year showed that parties and leaders needed to work together to serve East Timor, one of the world's youngest nations and among the poorest in Asia.

"Together we can serve our society better," he said.

Gusmao is set to benefit politically from his role in negotiations that earlier this month settled the sea border between East Timor and Australia and provisionally set formulas for splitting oil and gas riches under the seabed.

He returned to East Timor to a hero's welcome last weekend with thousands of East Timorese lining roads to the country's international airport.