Warnings about a slowdown in the housing market were shrugged off by Rightmove, Britain's leading property website, as it announced a rise in profits for the first half.

The group said it had not seen any noticeable deterioration in its business from a cooling market - although Ed Williams, chief executive, acknowledged that a slowdown was taking place.

Concerns about the health of the property market have risen after the five increases in interest rates since the summer of 2006.

Mr Williams said there was a two-tier situation at present: "London has been performing very strongly in the last year while the rest of the country has seen a period of readjustment." But the overall market was not fading as rapidly as suggested by some reports, he said.

The group, which has a dominant position in its sector, has about 1m properties advertised at any time - about 90 per cent of all homes up for sale in the UK.

It makes money by charging estate agents and developers a set monthly fee per branch.

This year it has been able to raise that fee without losing customers.

Revenue for the six months to December 31 rose from ?15m to ?25.4m while pre-tax profits climbed from ?1.6m to ?12.1m.

Comparable figures the previous year were hit when Rightmove abandoned its ?7m project to set up a unit to sell home information packs (Hips).

The government U-turned last year on Hips, which require sellers to provide information on their properties. They will now apply only to larger dwellings.

Rightmove had set up a unit to sell these packs but was forced to abandon the project.

Mr Williams said on Friday "there is no way we would want to go back into it now".

The results were in line with a trading update in July which flagged that Rightmove should meet analysts' consensus of full-year profits of at least ?29.9m.

Ten per cent of earnings in the past few months have been from three new initiatives, Mr Williams said.

These were aboutmyplace.co.uk, where companies can do targeted advertising; holidaylettings.co.uk, which advertises holiday lettings; and Rightmove Choice, which gives customers more visibility on the website in return for higher payments.

Average revenue per advertiser per month rose 29 per cent to ?234 as a result of higher monthly charges and the impact of Choice.

Website traffic was up 58 per cent on the first six months of 2006 at 24.3m visits a month.

Earnings per share rose from 0.41p to 7p. It also plans to pay an interim dividend of 2p (1.5p). The shares rose 20?p to 583p.