DUBAI: A suspicious package destroyed at Bahrain's airport contained no explosives but a number of tools that can be used to make a bomb, police said on Wednesday, as security forces fired teargas on anti-government protesters in the capital.

Earlier, the interior ministry said a package containing explosives had been sent via Dubai from Britain, whose embassy was assumed to be the target of an explosion on Sunday caused by a bomb placed under a nearby vehicle.

"He (the director general of Bahrain International Airport police) said that after examining the package at the Ministry of the Interior's laboratories it was revealed that the materials in the package were empty from explosives, but they could be used in the making of an explosive device," said a statement on the police media website.

Britain's foreign office had also said it was looking into reports an explosive package had been sent to Bahrain from Britain.

In the capital, riot police wielding batons fired tear gas to prevent demonstrators from reaching Pearl Square, named after a statue torn down by security forces during a crackdown on protests led by Bahrain's Shi'ite Muslim majority.

The protests, which erupted in February, led the kingdom to call in troops from fellow Sunni-led Gulf states to help stamp out unrest it said was fomented by Shi'ite power Iran.

"There are at least 100 police jeeps trying to block marchers from getting to Pearl Square," an activist told Reuters by telephone. "I saw about 10 people suffering from tear gas inhalation and there were around three arrests".

Pearl Square was the rallying point for protesters until security forces tore down the statue and sealed off the area.

Protesters began marching after Shi'ite ceremonies marking the martyrdom of the Prophet Mohammad's grandson, Hussein, in the year 680, at the battle of Kerbala in what is now Iraq.

Bahrain earlier blamed protesters for the death of a woman on Wednesday who was struck on the head during unrest last month, but rights activists expressed doubt over the official explanation.

"A Bahraini lady who was injured in the head by an iron rod hurled by a vandal during rioting in al-Daih on 18 November died today," the Interior Ministry said in its Twitter feed.

Rights activists named her as Zahra Saleh and said it was not clear who injured her. They say there were clashes with police in al-Daih that day. Videos circulated by online activists seem to show her with a metal rod lodged in her head.

"We don't have details about the incident. There are no witnesses from the village," said Mohammed Al-Maskati, head of the Bahrain Youth Society for Human Rights.

"We have a video showing security forces carrying rods, but no evidence of who the attacker was, or if she was participating in protests or not. There were protests at the time." (Additional reporting by Mohammed Abbas and Firouz Sedarat)