Per Wikipedia:
Killer Force, also known as The Diamond Mercenaries, is a 1976 thriller film directed by Val Guest and starring Telly Savalas, Peter Fonda and Christopher Lee. It was a co-production between the Republic of Ireland, Switzerland, United Kingdom (post production at Twickenham), and the United States and was filmed primarily in Namibia (at the time of filming part of South Africa). Its plot is about a gang of criminals who plan a major robbery of a diamond mine.
Val Guest called it "a very tough picture to make."
This is a pure cheese b-movie with all the drippings of the 70's, and an odd cast to say the least. It was fun to see Christopher Lee in a commando-like role though.
There's nothing remarkable about this film, but if you like low budget movies to chuckle at, it may be worth a try.