The United States on Monday welcomed Myanmar's election as a victory for the Burmese people but said it would watch for the democratic process to move forward before making any adjustments to U.S. sanctions.

Supporters of Myanmar's Aung San Suu Kyi were confident on Monday her party had won a landslide victory in the country's first free general election in 25 years, with the biggest question whether the margin was enough to claim the presidency.

The U.S. State Department's top Asia diplomat cautioned against declaring a landslide when so few votes had been counted from Sunday's poll, but said preliminary indications were that the elections went "quite smoothly."

Daniel Russel, the U.S. assistant secretary of state for East Asia, added that after 50 years of military dictatorship, "this was a hell of a step forward for the democratic process in Burma."

However, he added: "Now comes the hard part."

Russel told reporters that for the United States and the international community to provide the kind of support Myanmar needed, the transition from the current government to the future administration "is going to have to be credible."

He said the senior leadership of the military in Myanmar, which is also known as Burma, had reaffirmed this week their commitment to abide by the results of the election.

"The United States, and I believe other members of the international community, have every intention of holding them to that," he said.

"Our expectation is that the military and the political leaders of Burma are going to have to listen."

Russel said it was too early to make pronouncements on the overall conduct of Sunday's voting and it was premature to say whether the election could lead to a lifting of remaining U.S. sanctions.

This would depend more than just on how the election day was conducted, he said.

"The next steps in terms of government formation, in terms of reconciliation, similarly, are going to have to move Burma in the right direction," he said.

"The further the process of reform moves, the more credible and respectable the political process is, the greater the support and the lower the hurdles for the U.S. government, and I suspect other governments, to actively support a new Burmese government, including through adjustments to our policies."