
The missive was sent through diplomatic channels from Bangkok to Burma's paramount leader Senior General Than Shwe in Nay Pyi Taw, a government source said.
Gambari, who was in Thailand between Sunday and Tuesday, had asked Surayud for help in requesting the Burmese generals to issue a longstay visa for him.
The envoy was taking this week to visit Malaysia, Indonesia, India, China and Japan to relay the UN's concerns over the grave situation in Burma and seek cooperation from Burma's neighbours to support his mission.
He plans to visit Burma again by the middle of next month to exert efforts to move the country toward democracy and national reconciliation after a crackdown on mass street demonstrations last month left at least 13 people dead.
More than 2,000 protesters including Buddhist monks were detained and are still subjected to interrogation.
Surayud sent his first letter to Burma early this month to express Thailand's distress over the situation and urge the Burmese junta to restrain from using force against the protesters, notably Buddhist monks.
His second letter urged the Burmese junta to open a political dialogue with opposition leader Aung San Suu Kyi to end the conflict and pursue national reconciliation.
Surayud has suggested forming a core group consisting of Asean plus China and India to deal with the Burma issue, similar to the sixparty negotiations over the North Korean nuclear standoff.
The Thai government was consulting with Singapore, which holds the rotating chairmanship of Asean, to explore ways to solve political problems in Burma, which is also an Asean member, the source said.
The 10 Asean leaders will meet at their annual summit in Singapore next month with the Burma case expected to be a dominant topic.
By Supalak Ganjanakhundee
The Nation