Burmese activists in Thailand and Singapore demonstrated Sunday against next month's constitutional referendum.

In Thailand, about 100 activists demonstrated outside Burma's Embassy in Bangkok.

The demonstrators, organized by the Joint Action Committee for Democracy in Burma, chanted slogans against the May 10 referendum. Protest organizers called the vote a ploy to help Burma's ruling generals keep their grip on power.

In Singapore, hundreds of activists, many wearing t-shirts with the word "No" printed on them, protested at the Burmese Embassy.

Both protests were peaceful.

In Tokyo Saturday, several demonstrators were injured and one man arrested during scuffles with police outside the Burmese Embassy there.

About 150 people were protesting at the embassy in Japan, demanding that all Burmese expatriates be allowed to vote in the referendum.

Expatriates whose government documents - such as visas and exits permits - are not up to date, are being excluded from the vote. That rule excludes most political exiles and refugees.

Burmese citizens living outside their home country have begun casting ballots for the referendum.

Burma's pro-democracy party in Rangoon says intimidation and violence are being used against opponents of the military-backed constitution ahead of the referendum.

The government says the new constitution will lead to multi-party elections in 2010.

Opposition activists have criticized the document, saying it has been drafted with no real public input, and enshrines the military's role in the country.

Some information for this report was provided by AFP and Reuters.