Myanmar's pro-democracy leader Aung San Suu Kyi told the mostly Karen refugees in Mae La camp in Thailand she will work to get them back to Myanmar as soon as possible.

Suu Kyi, who heads the main opposition party National League for Democracy in Myanmar's fledgling democracy, visited the camp near Mae Sot during a trip to Thailand.

The six-day visit was her first trip outside Myanmar in more than 20 years for fear the former ruling junta wouldn't have allowed her back in.

Mae La camp on the border with Myanmar is one of the largest in Thailand for ethnic Myanmar groups fleeing fighting between rebels and the military.

Suu Kyi was met by a cheering crowd of around 2,000 as her convoyed passed through the camp, a report by the Irrawaddy Web news site said.

"I won't forget you. I'll try my best for you," Suu Kyi told the crowd by loudspeaker.

At the news conference later she said her discussions with Thai authorities centered on conditions for Myanmar migrant workers in Thailand and conditions for the Myanmar refugees.

"These two issues are the most serious issues and I discussed the refugees' situation and the conditions that resulted in them becoming refugees," she said.

"I am satisfied with my discussion with the [Thai] authorities and I will do whatever we can to help solve these two issues as soon as possible," she said. "At this stage, it is only a discussion. No outcome has been achieved yet."

She said the goal was to create conditions in Myanmar, formerly called Burma, that will enable migrant workers and refugees to return home, the Irrawaddy report said.

Suu Kyi also cautioned potential investors in Myanmar over a "reckless optimism" that the democratic process is irreversible, saying the military still plays a prominent role in politics.

Her comments during her Thailand trip reportedly irritated the Myanmar's elected president and former senior junta leader Thein Sein who last week unexpectedly canceled his own 2-day trip to Thailand set for this week.

Thein Sein reportedly was unhappy about the possibility of being upstaged by Suu Kyi.

A report by The New York Times said an adviser to Thein Sein criticized Suu Kyi for her comments.

"Personally, I really admire her, but I have a doubt," the adviser, U Nay Zin Latt, said via e-mail, The Times report said, noting that public criticism of Suu Kyi is rare.

Suu Kyi and Thein Sein have been striving to improve their relationship since the military handed over power after elections in November 2010 to a nominally civilian government -- one-quarter of legislative seats are reserved for military appointees.

Suu Kyi, now a member of Myanmar's Parliament, won a national election 20 years ago but was refused power by the ruling military government.

She spent most the next 20 years under some form of detention and wasn't allowed to participate in the 2010 national election. However, she won a seat in April by-elections.

A particularly sensitive area for the government and its military and security force supporters is the continuing struggle to reign in ethnic rebels in several frontier states including.

The long-running fight with the Karen rebels as well as those in the Kachin, Shan and Mon states have dogged the military which ruled the country for most of the years since independence from the British in 1948.

Many of the rebel groups say they are fighting for more autonomy from the central government, formerly in Yangon and now in the newly built expansive city of Naypyitaw.

The rebels also want the landless and poor farmers to have more social and financial benefits from the exploitation of natural resources -- something many countries are keen to do now Myanmar is on the road to democracy, however tenuously.