Women will be offered £170 a week maternity pay for six months, after the birth of their first child, as part of a package of family policies to be unveiled by Charles Kennedy today.

The Liberal Democrat leader said the £4,420 "maternity income guarantee" was the equivalent of the minimum wage for someone on a 35-hour week.

At present, women get 90 per cent of their normal salary for the first six weeks of their maternity leave, followed by £102 for the next 20 weeks.

The Lib Dems say the change would leave 75 per cent of the 188,000 working women who have a first child each year better off.