PHNOM PENH (Reuters) - Newly re-elected U.S. President Barack Obama will go to Cambodia on November 18 to attend an Asian summit, a Cambodian minister said on Wednesday, adding to speculation he may use the opportunity to visit nearby Myanmar.

Myanmar is opening up after almost half a century of military rule and the United States suspended sanctions on the country earlier this year in recognition of the changes under way.

In November 2011 Hillary Clinton became the first U.S. secretary of state to visit in more than 50 years.

Many U.S. companies are looking at starting operations in the country, located between China and India, with abundant resources and low-cost labor.

Officials in Myanmar, also known as Burma, have not confirmed an Obama visit.

Cambodian Information Minister Khieu Kanharith said he did not know how long Obama would be in his country.

"We will have Obama and also (Russian President Vladimir) Putin and leaders from China and Japan," he told reporters.

The annual summit of the 10-country Association of Southeast Asian Nations (ASEAN) is usually extended to take in meetings with leaders of partner countries. Preliminary details for this year show the event will run from November 15 to 20.

Local media have said Obama may visit Thailand, like Myanmar an ASEAN member, while he is in Asia, but that could not be confirmed.

(Corrects second paragraph reference to half a century)

(Reporting by Prak Chan Thul; Editing by Alan Raybould and Jonathan Thatcher)