Two men who took part in the murder of black teenager Stephen Lawrence in 1993 -- a landmark case which exposed what an inquiry called the institutional racism of London's police force -- were given life sentences on Wednesday.

Judge Colman Treacy ruled that Gary Dobson should serve a minimum 15 years and two months and David Norris 14 years and three months.

This was a terrible and evil crime, he told a packed courtroom at the Old Bailey. This crime was committed for no other reason than racial hatred.

A totally innocent 18-year-old youth on the threshold of a promising life was brutally cut down in the street in front of eye witnesses by a racist, thuggish gang.

You were both members of that gang, he added. I have no doubt at all that you fully subscribed to its views and attitudes.

The minimum sentences reflect the fact that Dobson and Norris were under 18 when Lawrence was murdered in southeast London in 1993.

Dobson, now 36, and Norris, 35, were found guilty on Tuesday

after a six-week trial that hinged on new scientific evidence presented by prosecutors.

Lawrence was stabbed to death at a bus stop in an unprovoked attack by a gang of white youths. The trial had heard that at least three more people had been in the gang, all of whom are still at large.

The other people involved in the murder of Stephen Lawrence should not rest easily in their beds, Metropolitan Police Commissioner Bernard Hogan-Howe told reporters shortly before sentencing. We are still investigating this case.

We are actively reviewing the consequences of (conviction)yesterday ... and what opportunities that might give us for the future.

The Lawrence case became a catalyst for change after exposing deep-rooted failings in the Metropolitan Police, dominated by senior white officers in an increasingly multiracial society.

A 1999 report by senior judge William Macpherson said the murder had exposed institutional racism in the force and also accused officers of incompetence and a failure of leadership.

Since then, the police have overhauled their policies on racism and tried to recruit more officers from ethnic minorities.

(Reporting by Keith Weir; Editing by Steve Addison)