There should be no delay in easing sanctions against Burma if its moves towards democracy continue, David Cameron said today.
But the Prime Minister said he wanted to see the situation for himself before backing any relaxation.
Mr Cameron is due to become the first Western leader to meet democracy activist Aung San Suu Kyi since she was elected to parliament when he visits the country tomorrow.
Interviewed on BBC Radio 5 Live, the premier said he would also meet President Thein Sein and "thank him for the work that he has done" on democratic reform.
Asked if sanctions should be eased, Mr Cameron said: "If Burma moves towards democracy then we should respond in kind, and we should not be slow in doing that.
"But first I want to go and see for myself on the ground how things are going."
Some of the business delegation that has been accompanying Mr Cameron around South East Asia are due to travel to Burma.
However, Downing Street has insisted the visit is purely political and the businessmen will merely be carrying out "cultural" activities.
Malaysian Prime Minister Najib Tun Razak was asked at a joint press conference with Mr Cameron in Kuala Lumpur whether he thought sanctions should now be relaxed.
He said he had recently visited Burma and met President Thein.
"I really do believe first of all that he is sincere," Mr Najib said. "This has been supported by Aung San Suu Kyi's own personal remarks about him."
The premier said he was convinced the momentum to democracy was irreversible, and that view was shared by "many people" in Burma.
Sanctions should be eased quickly in order to shore up the president's popularity, he added.
"We need to support a man like President Thein Sein so he will be supported by the community, because there will be elements who want to take a much more conservative approach," he said.
Mr Cameron said developments in Burma may be "one potential chapter of light" in a "world where there are many dark chapters in history being written".
"Of course we should be sceptical. Of course we should be questioning. Of course we shouldn't be naive," he said.
But he added: "Aung San Suu Kyi herself, who has spent so many years in such a long, lonely but powerful struggle believes that he is acting in good faith."
Britain had played a "leading role" in the imposition of sanctions, and would also not be "backwards" in responding to positive changes, he added.
In a question and answer session with students at the Nottingham University campus in Malaysia later, Mr Cameron said: "I hope that following my meetings tomorrow I will have the confidence to go back to my country, to back to others in the European Union, and argue that the change in Burma is irreversible, that they are set on a path towards democracy, that in a world of difficulty and darkness and all sorts of problems, here is one bright light that we should encourage, and we should respond in a way that makes that regime feel that it is moving in the right direction and that the world is on its side."