Foreign Secretary William Hague has condemned the "flawed elections" which have taken place in Burma.
Voters in the south-east Asian country went to the polls for the first time in 20 years, but Mr Hague said the result was a "foregone conclusion" and that the ballot was not "free, fair or inclusive".
And he vowed the UK would "stand by" the people of Burma by keeping up sanctions on the ruling military regime until "real progress" on democracy, governance and human rights could be secured.
Candidates linked to the ruling junta are expected to secure a landslide victory in the much-criticised election, with around a quarter of seats reserved for the army.
Aung San Suu Kyi's main opposition party, the National League for Democracy, boycotted the poll and other opposition groups have fallen victim to complex election rules.
"We know the result of these elections is already a foregone conclusion," Mr Hague said.
"They will not be free, fair or inclusive. More than 2,100 political prisoners remain incarcerated, opposition and ethnic parties have been refused the right to stand and a quarter of the seats are already reserved for the military.
"Holding flawed elections does not represent progress. For the people of Burma, it will mean the return to power of a brutal regime that has pillaged the nation's resources and overseen widespread human rights abuses, including arbitrary detentions, enforced disappearances, rape and torture.
"The British Government will stand by the people of Burma and will continue to maintain pressure on the regime until we see real progress on democracy, governance and human rights."
Earlier, US President Barack Obama said the elections were "anything but free or fair", adding: "For too long the people of Burma have been denied the right to determine their own destiny."