Image copyright Reuters Image caption Radel had taken a leave of absence to seek treatment for substance abuse

A Florida congressman who pleaded guilty to cocaine possession has resigned from his seat.

Florida Republican Trey Radel had recently returned to Capitol Hill following a leave of absence and a stay in a rehabilitation clinic.

Radel, 37, admitted to buying 3.5g (0.12oz) of cocaine from an undercover police officer in October and was sentenced to a year of probation.

He said he had been struggling with alcoholism and substance abuse.

The first-term Republican sent a resignation letter to House of Representatives Speaker John Boehner on Monday.

"It is my belief that professionally I cannot fully and effectively serve as a United States Representative to the place I love and call home, Southwest Florida,'' he wrote.

His resignation was to be effective 18:30 local time (23:30 GMT) on Monday.

Florida Governor Rick Scott will next schedule a special election to replace him.

Mr Scott, along with other Florida Republicans, had called on Radel to step down after his drug conviction in November.

And Radel's critics noted he had voted for a measure that mandated drug tests for poor Americans who apply for food aid.

Radel, a former television journalist and chat show host, was elected in November 2012.