Thirty-two countries including the United States and Britain expressed concern on Monday about Bahrain's human rights record, urging the Western-allied kingdom to protect the right to peaceful assembly and address reports of torture.
The letter, read out by Switzerland to the U.N. Human Rights Council, welcomed "positive steps" by Bahrain to improve observance of human rights, including the creation of a unit to investigate abuses by security forces.
"However, the human rights situation in Bahrain remains an issue of serious concern to us," said the letter, read by Swiss Ambassador Alexandre Fasel.
"We are concerned about reports of harassment and imprisonment of persons exercising their rights to freedom of opinion and expression and of peaceful assembly and association, including human rights defenders," it said.
The letter said there were not enough guarantees to a fair trial and criticized the detention of minors who took part in demonstrations. "We are concerned there is insufficient accountability for human rights violations," it said.
Bahrain, home to the U.S. Navy's Fifth Fleet, was swept by unrest during the 2011 "Arab Spring" uprisings when majority Shi'ites, complaining of discrimination, demanded political reforms. The Sunni-led government denies discrimination.
Since then there have been sporadic protests and a growing number of bomb attacks that the government attributes to dissidents with links to Shi'ite power Iran. Iran denies any role in subversion or violence in Bahrain.
The Bahraini government said 17 policeman have been killed and 3,328 wounded since 2011 in bomb attacks or violence it says was stirred up by the opposition.
The opposition says the government is attempting to stifle free speech by jailing peaceful political dissidents.
The letter called upon the government "to appropriately address all reports of torture and ill-treatment of detainees and ensure full investigation and prosecution of these cases".
It also called on the government to agree to a visit by the U.N. Special Rapporteur on Torture. In 2013, the U.N. torture investigator said Bahrain had in effect canceled a trip he had planned to the Gulf Arab state.
Information Minister Isa Abdulrahman said that whenever individuals were questioned or imprisoned by the authorities it was due to a violation of the law and had nothing to do with freedom of expression or human rights.
"No one is immune from the process of the law in the Kingdom of Bahrain," he said.
"Our police exercise their duties in a very restrained manner," he said, noting that the statement had recognized the establishment of a special investigation of unit.
"If there is any claim of this [torture] whatsoever we encourage everyone to report it and there is due process."
He said 47 countries signed a similar letter last year and that this year's smaller number of signatories showed "more countries recognize the efforts that have been made by Bahrain."
He said the government denied security forces used excessive force in carrying out their work.
Human Rights Watch said it was "extremely disappointing" that countries like Italy and Spain had "put politics before rights and did not lend their voice in support of the joint statement".