Bahrain's interior ministry said on Wednesday that staff at its airport detonated a package of what were thought to be explosives that had originated from Britain.
"Concerned bodies of MOI (Ministry of Interior) exploded a package containing explosives found at the Airport coming from UK through Dubai," the ministry said on its Twitter account.
The ministry said the "investigation continues," in its initial brief statement.
But it later tweeted an update, saying "after examining package at lab it turns the materials used aren't explosives, but contained tools used to make explosives."
The report comes three days after a small explosion at a bus parked near the British embassy in the Bahraini capital, without causing any casualties.
Five other cars parked in the area were also damaged in the bus blast, an interior ministry spokesman said at the time, adding that security had been boosted around embassies.
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Britain said it was in contact with Bahrain's interior ministry over Sunday's incident.
The scares come after the British embassy in Tehran was ransacked on November 29 by a pro-regime mob after London slapped new sanctions on Iran over its disputed nuclear programme.
Sunni-ruled Bahrain was rocked by Shiite-led pro-democracy protests between mid-February and mid-March. It accuses Shiite-dominated Iran of backing unrest in the kingdom, a charge denied by Tehran and the opposition.
On Friday, Britain's Daily Telegraph newspaper reported that former British police boss John Yates and US ex-cop John Timoney will oversee reforms to Bahrain's security force after a report found it guilty of human rights abuses.
A special independent commission probing Bahrain's crackdown on protests in February-March said on November 23 that police had used "excessive force" and tortured detainees, prompting King Hamad to vow reforms.
The king commissioned the report to investigate allegations of government misconduct and human rights abuses against protesters, democracy activists and opposition figures.
The death toll from Bahrain's uprising reached 35, including five security personnel, the report found. Five detainees were tortured to death while in custody and hundreds were also injured.