Steel magnate Lakshmi Mittal's family members have once again topped the list of Britain's wealthiest people with a fortune of £17.5 billion ($28.6 billion), according to  Sunday Times newspaper.

The newspaper is set to release in its Sunday edition the annual rundown of Britain's 1,000 richest individuals and families.

The 1,000 richest people in Britain increased their collective wealth by 18 per cent in the past year and are now worth £395.8 billion ($647.8 billion), said the Sunday Times.

The Mittals held onto their position as the wealthiest people in Britain, but they are 22 per cent poorer than a year earlier thanks to a drop in the share price of ArcelorMittal, the report said.

Fellow metals mogul Alisher Usmanov, a Russian who has a stake in English football club Arsenal, saw the biggest increase in wealth, it added.

Usmanov climbed six spots on the list to number two after adding £7.7 billion to his fortune. He is now worth £12.4 billion, according to the list.

The Duke of Westminster fell out of the top three for the first time since 1999 despite adding £250 million to his fortune. The Briton owns huge parcels of land in central London and elsewhere.

For the first time, more than 100 women made the cut - a feat that this year required a fortune of at least £70 million. In 2010, the bar was set at £63 million while in 2008 it was £55 million.

The study shows that the number of billionaires in the UK now stands at 73 - up from 53 a year earlier but just shy of the record of 75 set in the pre-crisis list of 2008, when the collective wealth of the top 1,000 was £413 billion.