WASHINGTON (Reuters) ? Berkshire Hathaway Inc. has received US antitrust approval to acquire the North American unit of Swiss reinsurer Converium Holdings AG , US officials said yesterday.

Antitrust authorities completed their review of the $295 million deal without taking any action to block it, the US Federal Trade Commission said in a notice.

The North American unit was the main source of Converium?s financial turmoil in 2004, when it was forced to raise emergency capital after discovering a $500 million hole in claims reserves and closed down the unit to new business.