Two men are trapped in car on the Federal Highway, 2km south of Sutton.

Police have closed one of two southbound lanes on the highway as the ACT fire brigade work to rescue the men, who are said to be in a serious condition.

The single vehicle accident happened at about 2.40pm this afternoon.

The SnowyHydro South Care helicopter's Twitter account announced about 3.10pm the helicopter had been tasked to a Federal Highway motor vehicle accident near Lake George, but NSW Police could not confirm if it was attending the same accident.

More to come.