THE fate of Diana, Princess of Wales, was raised by the former Chief Rabbi last night, in a passionate defence of marriage.

In a toughly worded Lords speech about selfishness in society and broken marriages that result, Lord Jakobovits spoke of the affair between the Princess - after her divorce from the Prince of Wales - and Dodi Al Fayed.

He said: ''The People's Princess would still be alive and so would her lover if they had observed absolute fidelity within marriage as an inviolate principle. What a price the nation had to pay for marital infidelity.''

Lord Jakobovits, in a debate on the role of marriage, also hit out at Chancellor Gordon Brown for scrapping the married couple's allowance in the Budget and Home Secretary Jack Straw for saying the state should not make moral judgments about marriage.

''Are the present depressing trends reversible? Of course they are, provided we have the will to reverse them and to stop encouraging the further erosion of marriage.''

He protested: ''The Home Secretary, in a television interview the other day, argued that the Government, now representing a secular state, should altogether withdraw from moral judgments affecting marriage.

''When the stability of the home is no longer the business of the Home Secretary, then clearly the last ramparts protecting the home are crumbling.

''The Foreign Secretary has gone further. The moral values of his policies are for exports to distant overseas communities, but not reflected in the stability of marriage at home.

''And the Chancellor has removed the last financial prop to the encouragement of marriage.

''We have already paid an extortionately high price as a nation for our indifference to marriage,'' said Lord Jakobovits.

Labour ex-Cabinet minister the Earl of Longford, a prominent Roman Catholic, declared: ''Sex outside marriage is a sin. Once you accept that, either you accept marriage or the human race dies out.''