Britain's right-wing U.K. Independence Party says one of its European Parliament members is in serious condition in a hospital after an "altercation" with colleagues.

Party leader Nigel Farage said Thursday that "following an altercation that took place at a meeting of UKIP MEPs this morning ... Steven Woolfe subsequently collapsed and was taken to hospital. His condition is serious."

The euroskeptic party was instrumental in getting Britain to hold a referendum on EU membership, which ended in a June 23 vote to leave. Since then, however, it has been torn by infighting.

Long-time leader Farage stepped down after the referendum, and was replaced by Diane James. She quit Tuesday after just 18 days — leaving Farage interim leader.

Woolfe had announced his intention to run in an upcoming leadership UKIP contest.