US Secretary of State Hillary Clinton said Tuesday that Washington is taking concerns about military cooperation between nuclear-armed North Korea and Myanmar "very seriously".

Clinton said as she arrived in Thailand ahead of Asia's biggest security forum that such links between the hardline communist state and military-ruled Myanmar could destabilise the region.

Speaking after talks with Thai Prime Minister Abhisit Vejjajiva, she also expressed fresh concerns about the rights record of Myanmar's ruling junta, including allegations that the army was abusing young girls.

"We know that there are growing concerns about military cooperation between North Korea and Burma which we take very seriously," Clinton told reporters in Bangkok, calling Myanmar by its former name.

Fears about military cooperation between the two so-called pariah states escalated after a US Navy destroyer last month began tracking a suspect North Korean ship that was reportedly heading for Myanmar.

The vessel came under scrutiny under new United Nations sanctions designed to punish Pyongyang over a recent underground nuclear test and a series of rocket launches including a long-range projectile.

Separately a group of exiled Myanmar activists last month released pictures of what they said was a secret network of tunnels built by North Korean experts inside Myanmar.

Such cooperation would be "destabilising" for southeast Asia, Clinton said.

US officials with Clinton said the concerns she was describing had come from within the region and referred to the delivery of small arms.

Myanmar and North Korea, both of which are severely criticised internationally for human rights abuses, restored diplomatic relations in 2007 after a 24-year rift.

Clinton added that Washington was "deeply concerned by the reports of continuing human rights abuses within Burma and particularly by actions that are attributed to the Burmese military concerning the mistreatment and abuse of young girls."

Clinton arrived in Thailand from New Delhi ahead of Thursday's Association of Southeast Asian Nations (ASEAN) Regional Forum on the tourist island of Phuket, which is expected to focus on North Korea and Myanmar.

US officials said a key thrust of her debut appearance at the ARF would be how to crank up the pressure on Pyongyang to return to multilateral nuclear disarmament talks.

They said Clinton would meet one-on-one with her counterparts from South Korea, China, Japan and Russia -- which along with the United States were North Korea's partners in six years of disarmament negotiations.

Pyongyang's foreign minister has declined to attend the security forum, instead sending a roving ambassador to the grouping of 27 nations.

The US State Department has been coy on whether Clinton would meet any North Korean delegates in Phuket.

The forum will also face the perennial challenge of Myanmar, which has sparked outrage by putting pro-democracy icon Aung San Suu Kyi on trial over an incident in which an American man swam to her lakeside house.

Clinton is also expected to discuss the region's economy and action on swine flu, and will hold an unprecedented meeting with counterparts from Vietnam, Laos and Cambodia.

The ARF will also tackle terrorism after suicide blasts Friday at two hotels in Jakarta, the capital of Indonesia, a key ASEAN state that Clinton visited in February on her first overseas tour as secretary of state.

Clinton will also sign a non-aggression pact with ASEAN in a bid to counter the influence of China.

During her visit to New Delhi and Mumbai, Clinton said she had reassured her hosts that President Barack Obama would not only maintain but deepen a "strategic partnership" launched under his predecessor George W. Bush.

Deals were struck paving the way for billions of dollars in exports of civilian nuclear reactors and military hardware to India, but differences remain between New Delhi and Washington over climate change.