BANJUL (Reuters) - Gambia's ministers for finance, foreign affairs, trade and the environment have resigned from President Yahya Jammeh's government, according to ministry sources and state television.

The veteran leader lost a Dec. 1 vote to president-elect Adama Barrow who is due to be sworn in on Thursday. Jammeh conceded defeat but now says he will not step down. Regional leaders have threatened sanctions or military intervention to remove him from power.

(Reporting by Pap Saine; Writing by Matthew Mpoke Bigg; Editing by Dominic Evans)