Authorities in Bahrain, which has been rocked by protests for two years, have voiced "dismay" over an assessment by the US State Department of the rights situation in the kingdom.

"The report includes texts which are totally far from the truth, adopting a manner that fuels terror and terrorists targeting Bahrain's national security," state news agency BNA late on Wednesday quoted government spokeswoman Samira Rajab as saying.

The strategic tiny kingdom of Bahrain, home to the US Fifth Fleet, has been hit since February 2011 by a wave of Shia-led protests calling for the ouster of Prime Minister Sheikh Khalifa bin Salman al-Khalifa in office since 1971.

A US State Department report released on April 19 said that "the most serious human rights problems included citizens' inability to change their government peacefully; arrest and detention of protesters on vague charges, in some cases leading to their torture in detention."

It criticised the "lack of due process in trials of political and human rights activists, medical personnel, teachers, and students, with some resulting in harsh sentences."

The report claimed that "discrimination on the basis of gender, religion, nationality, and sect persisted, especially against the Shia population" which makes up a majority in Bahrain, ruled by the Sunni Al-Khalifa dynasty.

Rajab "deplored the report for lacking objectivity, totally siding with the terrorists who seek to sow chaos in the whole region."

Bahrain refers to protesters who clash frequently with police forces in Shia villages as "terrorists" it claims are backed by Shia-majority Iran.

The kingdom "reiterated full commitment to comply with the human rights principles and standards in confronting terror which targets Bahrain and innocent civilians," said Rajab.

The State Department report acknowledged that "some protesters engaged in lethal acts of violence against security forces, including the use of improvised explosive devices, Molotov cocktails, and other improvised weapons."

Rajab in her statement "urged the US State Department to help countries protect their national security and back their stability, the way the US itself does in the war it is waging on global terror."

UN torture investigator trip cancelled

Meanwhile, the UN torture investigator said Bahrain had effectively cancelled a trip he had planned to the Gulf Arab state.

Juan Mendez, the UN Special Rapporteur on Torture, said in a statement it was the second time a scheduled visit had been postponed at short notice. His trip had been set for May 8-15.

"It is effectively a cancellation as no alternative dates were proposed, nor is there a future road map to discuss," he said on Wednesday.

"Let me be clear, this was a unilateral decision by the authorities."

Mendez said "this postponement could be perceived as if there is something to hide."

Bahrain's state news agency said on Monday the authorities had asked Mendez to delay his trip, without giving a reason.

Mendez then put it off until further notice, the agency said.