A suspected bomb blast has killed two people in Laos even as US Secretary of State John Kerry was visiting the tiny southeast Asian country.

The blast occurred in Xaysomboun province, Xinhua reported citing Chinese embassy in the Laotian capital Vientiane.

The Chinese victims were on board a vehicle when the incident happened on Sunday. The Chinese officials described the blast as an 'attack'.

John Kerry's visit to Laos is a rare top level diplomatic outreach from the US. It comes after the Communist rulers of the Lao People's Democratic Republic chose a new leader last week.

The US had dumped more than two million tonnes of munitions in Laos during the Vietnam war and thousands of unexploded ordnance is a bane to the country.

It is believed that at least 50,000 people have died from explosions since the end of the war as more 30 per cent of the devices had remained unexploded.

China is the largest investor in Laos with Beijing flooding the communist country nation with projects with a view to expanding its sphere of influence in the region.

A top level Chinese delegation is due to visit Laos this year. President Barack Obama will also travel to the county later this year to take part in a summit of South-east Asian countries.