has attracted almost a million new UK users over the past three months, as a result of an aggressive new ad campaign, as well as a revamp of its search engine.

The search engine, which trails behind rivals Google, Yahoo and Microsoft in terms of market share, has seen its visitor figures rise from 4.54m to 5.48m, according to figures from Nielsen//NetRatings.

It launched a guerilla style marketing campaign earlier this year, placing ads on tube trains and various other places, encouraging people to ‘stop the online information monopoly’, claiming many people use Google without even thinking about the alternatives.

The company also overhauled its service last month, with the introduction of Ask 3D, which delivers results from different media types on the same results page, similar to Google’s Universal Search.

In the same period, Microsoft’s Live Search gained only 150,000 users, up from 5.53m to 5.69m. Ask appears to have attracted a number of users from Yahoo, as its visitor numbers dropped from 6.56m to 5.74m.

While these results are encouraging for Ask, it still has a long way to go to catch up with the big three search engines, especially in the US.

The latest comScore search market share figures put Ask’s share at 5%, compared with Microsoft on 13.2% and Yahoo on 25.1%. Google received 49.5% of searches.