Blast but "no bomb" in Pakistani cities

ISLAMABAD (Reuters) - A loud blast alarmed residents and security officials in the Pakistani capital, Islamabad, and nearby city of Rawalpindi on Monday but police later said it appeared it had been a sonic boom.

Residents of both cities heard a big blast just before 11a.m. (6 a.m. British time).

"We have checked everywhere in Rawalpindi, all the mainareas and hospitals, but there is nothing," a senior citypolice official said about 45 minutes after the blast washeard.

"It could have been a sonic boom but we are stillinvestigating."

A Pakistani air force spokesmen said none of their aircrafthad been over the city at the time of the blast.

A military official said there had been no bomb at any ofthe main military installations in Rawalpindi, the headquartersof the Pakistani army and the home of President PervezMusharraf.

Militants have launched several bomb attacks in bothRawalpindi and Islamabad over the past year.

The Taliban militant commander held responsible for most ofthe attacks threatened on the weekend to retaliate for agovernment offensive against militants in a northwestern regionon the Afghan border.

(Reporting by Augustine Anthony and Kamran Haider; Writingby Robert Birsel; Editing by Jerry Norton)