Foreign ministers meeting in Luxembourg also repeated calls for the release of political prisoners including opposition leader Aung San Suu Kyi, who has been held under house arrest for most of the past 14 years.
Myanmar's government has refused to recognise a victory for her National League for Democracy (NLD) in the country's last elections held in 1990.
|Members of the opposition NLD are gathering for a rare meeting in Yangon [Reuters]
The extension of sanctions came as NLD members gathered in Yangon on Tuesday for a rare meeting to discuss political issues including next year's planned elections.
According to Nyan Win, the party spokesman, those attending the meeting are to consider proposals for the 2010 vote, but might not decide about whether to take part.
The government was reported to have stepped up security in the former capital ahead of the meeting.
About 100 NLD members from various parts of the country registered at the party headquarters on Monday to attend the two-day meeting, Nyan Win said.
They include elected candidates from the 1990 general election whose results were annulled by the military.
Police were deployed near NLD headquarters on Monday while dozens of plainclothes policemen watched the building from across the street and a convoy of four to seven trucks carrying anti-riot police cruised the city.
The NLD maintains that the elections will take place under a constitution designed to ensure military's continued domination of politics.
The constitution also has clauses that will bar Aung San Suu Kyi from office.
The party has repeatedly urged the government to review the military-backed constitution, saying it was "approved by force'' in a referendum last year.