Miami (AFP) - Authorities in Florida suspended the upcoming execution of a death row inmate, after the US Supreme Court found problems with how the state sentences people to death.

The southeastern US state's high court suspended until further notice the lethal injection of Cary Michael Lambrix, scheduled for February 11, it said in an order.

It was the first such move by court officials since the US Supreme Court last month declared Florida's capital punishment system unconstitutional since the state was not guaranteeing the people's right to an impartial trial on whether the death penalty is imposed.

Unlike other US states, Florida state law allowed a jury to recommend execution, or not, but it left the deciding authority with the judge.

Lambrix, 55, was convicted of the 1984 murders of a man and a woman. He has always maintained his innocence.

His lawyers sought the stay of execution as Lambrix marked more than three decades on death row.