Mark O'Hara joins Motherwell on loan from Peterborough

"We have been chasing him for a number of windows now, so we are delighted to have him.

Craig Tanner and Adam Livingstone earlier left Fir Park, the latter on a temporary basis.

Tanner has not played for the first team for almost 18 months but returned to reserve action in recent weeks following a serious knee injury.

Motherwell handed him a short-term deal after the end of last season to help get him back to fitness and the 24-year-old rejected the offer of a an extension to January.

"We are disappointed Craig has chosen to leave, but we respect his decision," Robinson said.

"It's been a long road back to fitness for him and he'd done brilliantly well to get back onto the pitch and playing football again.

"We were keen to continue that push for match sharpness. But Craig has decided he'd rather continue his career elsewhere and we wish him all the very best of luck."

Left-back Livingstone, 21, has joined Morton on loan for the rest of the season.