Hundreds of guests were evacuated from the Royal Meridien Hotel on Wednesday after a small bomb exploded in a toilet on the ground floor.
A man who did not identify himself telephoned The Associated Press and said: “We put two bombs in the Meridien Hotel. Tell the government we can reach wherever we want to reach.”
The second bomb was discovered near the first one and defused, a security source said.
No one was injured in the blast at the hotel, where an international oil conference had opened earlier in the day. The source, speaking on condition of anonymity, said the bomb blew a hole in the ceiling and a door.
Bahrain, a financial hub in the Persian Gulf, has seen a revival of street protests by young Muslims, mainly Shiites, demanding political and economic reforms.