Many business people rely on their Blackberry to stay in touch

The Blackberry device, owned by Canadian firm Research in Motion, is popular among business people who rely on it to keep in touch with the office.

The service began to fail at about 1530 EST (2030 GMT) and users struggled to retrieve information for three hours.

The firm said no messages were lost and apologised for the problems.

However, many users were deeply unhappy.

"I don't know what happened, I don't care what happened. They need to save their excuses for someone who cares," said Stuart Gold, director of field marketing for Web company Omniture.

But others saw it as a welcome break from the daily grind.

"It made my life a little bit easier, since I didn't have to reply," Liberal Party spokesman Jean-Francois Del Torchio said from Parliament Hill in Ottawa.

Research in Motion has about 12 million subscribers worldwide.

Some users consider it so essential that the device has been dubbed the "Crackberry".