Google continues to dominate the search sector commanding over 55 per cent of the market share and gaining ground at the expense of rivals Microsoft and Yahoo.

Figures for April from Nielsen/Netratings show that Microsoft's minor resurgence in the market in recent months seems to have come to a halt.

Microsoft experienced its first market share increase for over a year in February, another in March, but has slipped from 10.1 per cent to nine per cent in April. In the same period Google increased its share by two per cent gain.

AOL remains in fourth place but has seen its share slip to 5.4 per cent from 5.8 per cent in March, while Ask.com stayed in fifth place with 1.8 per cent of search queries.

Microsoft recently purchased Aquantive in a move away from the search advertising market following Google's purchase of advertising broker DoubleClick.

But a spokesman for Microsoft said the company is not necessarily switching its focus away from the search advertising market.

'Microsoft is intensely committed to creating a thriving advertising business and to partnering closely with all key constituencies,' he said.