WASHINGTON (AFP) - President Barack Obama plans to visit Laos next year to attend a regional economic summit, making him the first US president to visit that country, an adviser said.

Mr Obama will make history when he attends an Association of South-east Asian Nations (Asean) conference in the poor but economically growing country, which was massively bombed by the United States during the Vietnam War, National Security aide Ben Rhodes said on Wednesday (Nov 4).

Speaking at a Washington think-tank, he said his own recent visit to Laos had helped lay the groundwork for Vientiane's 2016 chairmanship of Asean.

The US President will travel to Malaysia later this month to participate in this year's Asean summit. He has made a point of attending as his administration seeks to boost the group's standing and underscore the seriousness of an announced US "pivot" towards Asia and the Pacific.

Touching on a bitter past between Laos and the United States, Mr Rhodes said Washington could do more to clear unexploded ordnance that has lain menacingly in the country's fields since the Vietnam War.

US warplanes dropped more than two million tonnes of ordnance on Laos from 1964 to 1973 in some 580,000 bombing missions aimed at cutting North Vietnam supply lines through the neighbouring country.

An estimated 30 per cent of the ordnance failed to detonate.

Laos and the US have improved relations during Mr Obama's presidency; US ties to Vietnam and Myanmar have also been strengthened.

In 2012, Mrs Hillary Clinton, now a Democratic presidential hopeful, became the first US secretary of state to visit Laos in more than a half-century.