A Google status page said the service appeared to be malfunctioning around 1040 GMT, with the outage continuing more than three hours later.

"We're aware of a problem with Google Talk affecting a majority of users," the status page said.

"The affected users are able to access Google Talk, but are seeing error messages and/or other unexpected behavior."

At 1340 GMT, the page said, "we are continuing to investigate this issue."