DHAKA (Reuters) - Bangladesh’s main opposition alliance has written to the Election Commission seeking action to end what it says are violent attacks against its workers by ruling party activists and the arrests of candidates on trumped up charges.

At least 14 candidates in the Dec. 30 election under the National Unity Front alliance have been arrested in “fictitious cases” in recent weeks, the alliance said in a letter dated Tuesday, a copy of which was seen by Reuters.

Some 1,500 opposition workers have suffered injuries since Dec. 2, an alliance spokesman said separately.

Elections in Bangladesh are often marred by violent clashes, but the opposition alliance says the ruling party is trying to cripple its campaign by locking up, threatening and attacking its workers.

“We demand immediate release of these candidates on bail and also request issuance of instructions that no further candidates be arrested with an intention to harass,” the alliance said, also accusing the police of aiding the attacks, often dressed in plainclothes.

“The Higher Court must issue directives on forbidding any law enforcers performing duties in civil dress,” it said.

Prime Minister Sheikh Hasina’s Awami League, which is seeking a third straight term in power, has denied the allegations.

Police spokesman Sohel Rana said people could file complaints and “we will look into the allegation and take proper action”.

Chief Election Commissioner KM Nurul Huda did not respond to calls requesting comment.

The opposition letter comes after Mahbub Talukdar, one of the five commissioners that make up Bangladesh’s Election Commission said there was “no level-playing field at all” between contesting parties. His comments were dismissed as “untrue” by Huda.

Hasina’s government, while credited for improving Bangladesh’s economy, has been criticized by rights groups for suppressing dissent and sweeping arrests of opposition workers.

Violent clashes have broken out across the country since campaigning began last week, and two Awami League workers have also died.

More than 20,000 paramilitary troops have been deployed and the army is scheduled to be deployed on Dec 24.