Myanmar's president pledged to seek "lasting peace" with armed rebels and issued a plea for the nation's support, as ethnic unrest continues to marr reforms.

Thein Sein, a former general who came to power last year when outright military rule ended, has launched efforts to end decades of ethnic conflict as part a raft of landmark reforms in recent months.

Myanmar's quasi-civilian regime has reached tentative peace deals with several rebel groups including in eastern Karen and Shan states, but fighting in Kachin which borders China in the north has created uncertainty over the progress of reconciliation efforts.

"Participation of the entire national people is sorely needed to bring internal armed conflicts to an end and build lasting peace, and in nation-building endeavours," Thein Sein said in a message carried by state media on Sunday.

The address for Union Day, which marks the signing of a historic agreement with the country's disparate ethnic minority groups in 1947, said the government was "determined to keep on promoting democracy peacefully".

He said people would be "overjoyed" to see democratic elections and "equal participation in state affairs", reiterating a vow to focus on good governance and improve the rule of law.

The regime has won cautious applause -- and a slight lifting of Western sanctions -- for reforms including the release of political prisoners.

Democracy icon Aung San Suu Kyi is now campaigning to enter parliament in April 1 by-elections, a development which will likely bestow legitimacy on a parliament that came into being after controversial November 2010 polls.

An end to ethnic conflicts is a key demand of the international community, and the United States called for Myanmar to address "serious human rights abuses" in Kachin earlier this month.

In December, Thein Sein issued an order for the military to cease attacks against guerrillas from the Kachin Independence Army (KIA), but the move failed to stop unrest.

One of Myanmar's most prominent rebel groups, the Karen National Union (KNU), has warned its peace deal was fragile because continuing fighting in other ethnic areas was eroding trust in the government.

Myanmar's junta often invoked the prospect of civil war, which has wracked parts of the country since its independence in 1948, as an excuse for its near half century grip on power.