Bahrain's Sakhir circuit has filled troublesome drains with concrete and carried out additional welding work after loose covers halted last week's Formula One testing for Saturday's season-opener.

The governing FIA said in a note on Wednesday that remedial works had been carried out around turns seven and 11, with welding at certain areas around the track.

Triple world champion Max Verstappen said last week more checks were needed after testing was halted two days in a row amid fears the latest high-downforce cars were making such incidents more likely with their aerodynamic suction.

"Maybe these kind of things can be checked a bit more," said the Red Bull driver. "We know that this is a potential problem with these cars and when you go to certain tracks you know where the drain covers are."

The separate incidents revived memories of a more serious one that caused considerable and costly damage to Carlos Sainz's Ferrari during practice for last November's inaugural Las Vegas Grand Prix.

(Reporting by Alan Baldwin in London, editing by Christian Radnedge)