Hundreds of government workers in Burma were forced to vote in favour of an army-drafted constitution in non-secret ballots, held more than a week before a May 10 referendum, some of the workers said.

In one of the cases, about 700 employees in the Ministry of Electric Power-2's Yangon office were forced to tick their ballot papers with local referendum officials observing, witnesses said.

"We were all shocked and some people were furious but they couldn't do anything," said one of those present on Wednesday, who did not want to be identified for fear of recrimination by the former Burma's military rulers.

"They said those who wanted to vote 'no' had to hand in their resignation," the worker said.

In the United States on Thursday, President George W. Bush said the vote in Burma would not be "free, fair or credible" and imposed new sanctions on Burmese state-owned companies to put pressure on the military junta.

Bush said in a statement that junta leader Than Shwe and his regime were ensuring the referendum vote would be on a dangerously flawed constitution, adding they continued to ignore calls from the Burmese people and the international community.

OPPOSITION CALL TO REJECT CHARTER

Civil servants in government ministries in Naypyidaw, the generals' new capital 240 miles (390 km) north of Yangon, also reported advance voting in which they were forced to endorse the charter.

"They even told us to ensure that all our family members vote 'yes'. I'm really angry with myself because I couldn't do anything," one of them, an educated middle-ranking officer, told Reuters.

"I have to stick it out because of my family. I've never felt more humiliated in about 20 years service here. I really wish I had voted 'no'," he added.

The constitution is a key component of the generals' seven-step "roadmap to democracy" that is meant to culminate in multi-party elections in 2010 and bring an end to nearly five decades of military rule.

However, the opposition National League for Democracy (NLD) has rejected the charter since it guarantees the army a quarter of seats in parliament, control of key ministries and the right to suspend the constitution at will.

Officials from the NLD, which won a 1990 election landslide only to be denied power by the military, were not immediately available to comment on the forced voting allegations.

In a May Day (May 1) statement, the NLD reiterated its call for workers and farmers to oppose the charter, while Than Shwe urged them to approve it.

"I would like to urge the mass of the workers to take part in the tasks of whatever role they are in for approval of the draft constitution of the Republic of Burma," he said in a message carried by state-run newspapers on Thursday.