Montgomerie won seven successive European Order of Merit crowns and more than £12m in prize money with McLean carrying his bag.

But the 38-year-old has not claimed a tournament victory since the Scandinavian Masters last August - his longest barren spell for seven years.

Montgomerie announced the split on the eve of the Benson and Hedges International at The Belfry but insisted it was amicable.

"It was a very difficult thing to do, but we will remain very good friends," said Montgomerie.

"It's been the best relationship that European golf has seen and Alastair has been excellent, but there comes a time when you have to look at other options.

"It's just a professional decision. The sole reason is to see if it can bring me more success. I'm looking forward to the new challenge."

Montgomerie will team up with South African Jason Henning - brother of tour player Nic - for this week's tournament but it is a temporary measure.

Henning is the regular caddie of Swede Robert Karlsson, who is taking the week off.

Montgomerie and McLean's final tournament together was last week's French Open, when the Scot led after an opening 67 before slipping down the field to 23rd.

McLean celebrated 31 tournament wins with Montgomerie and was with him when he reached world number two in 1996.

They also shared the disappointment of near misses in the 1994 and 1997 US Opens and the 1995 US PGA championship.