BANGKOK/WASHINGTON (Reuters) - Washington has called a delay of a general election to return Thailand to democracy - to be held in February 2016 at the earliest, a deputy prime minister said after talks with a United States diplomat on Tuesday - was "unwise and unjustified". The military government, established after a May 22 coup, said last month an election planned for late 2015 would be delayed until 2016, giving more time for reforms which the military says should bring stability after a decade of factional rivalry.

A spokesman for the US State Department said Washington believed Thais should be allowed to choose a democratically elected government "as soon as possible". "We ... believe a delay until 2016 would be unwise and unjustified," the spokesman added.

On Tuesday, Deputy Prime Minister Wisanu Krue-ngam clarified the target date after talks with US Charge d'Affaires W. Patrick Murphy. "I told the U.S. charge d'affaires today elections will take place at the earliest in February 2016," Mr Wisanu told reporters. "But if we have to have a referendum, polls could be delayed by a further three months," he said, referring to a possible plebiscite on a new Constitution.

The United States, a long-time ally of Thailand, expressed dismay at the coup and froze US$4.7 million (S$6.21 million) of security-related assistance, cancelled high-level engagements, some military exercises and training programmes for the military and the police.

The May coup followed months of establishment-backed protests against a populist elected government.

A junta-appointed National Reform Council last week proposed stripping Parliament of the power to appoint a prime minister and Cabinet.

On Tuesday, a committee appointed to draft a new Constitution rejected that recommendation.

A senior Western diplomat said he was not optimistic about the possibility of an election in 2016, fearing Prime Minister Prayuth Chan-ocha, the army chef who launched the coup, could come up with a justification to delay. "It is not inconceivable that Prayuth will stay in power for two to three years," said the diplomat, who declined to be identified.

Questions over the return to democracy come at a time of extreme sensitivity surrounding the monarchy, in particular the issue of succession, which has formed part of the backdrop to the complex national crisis.

King Bhumibol Adulyadej, 87, is in hospital recovering from gallbladder surgery. The king is regarded as almost divine by many Thais and is widely seen as a unifying figure through years of political unrest.