Chris Wilder explains why Sheffield United made late move for Birmingham City striker

The 33-year-old has signed a deal until the end of the season with the option for a further year.

Donaldson becomes United's tenth recruit of the summer window.

Boss Chris Wilder said: "We have watched Clayton a lot, most recently for Birmingham at Burton, and it is clear that he will be a useful addition for us.

"He offers additional pace and power at the top end of the pitch and his Championship experience will be of value."

Donaldson began his professional career at Hull City and spent time out on-loan at Harrogate Town, Scarborough and Halifax Town, prior to making his name at York City, where he averaged just short of a goal in every two games.

A season in Scotland with Hibernian followed, prior to another prolific spell back in England with Crewe Alexandra.

In July 2011 the Jamaican international joined Brentford on a free transfer and during three seasons at Griffin Park he averaged better than a goal in every three games.

He moved to Birmingham in the summer of 2014, where he has scored 33 goals in 102 league starts.