The number of people clicking on ads which run alongside Google search results increased sharply in April, according to new data.

So-called 'paid clicks' for Microsoft and Yahoo! - which are a measure of how much revenue search firms generate from advertising - declined in the same period, according to comScore.

The figures were welcome by Google investors, who had been spooked by similar data earlier in the year which suggested that the growth in the search company's paid clicks had slowed significantly in the first quarter.

Google shares rose 2.6 per cent to close at $583 yesterday. According to comScore, Google showed a 20 per cent growth in the number of paid-for clicks in April as compared with the same month a year earlier.

Yahoo!'s paid-for clicks declined by 4.4 per cent and Microsoft's fell by 9 per cent over the same period.

Paid clicks refer to the number of times a person has clicked on one of the sponsored links which appear to the right of a list of search results. They are not an outright indicator of advertising revenue, but are a useful barometre of how search companies - which make the bulk of their money from ads - are performing.

Advertisers bid on the right to have their link displayed next to search results displayed for a given query.

In March, the growth in Google's paid clicks as reported by comScore was below analyst expectations for the second consecutive month, sparking fears that the search giant - which handles 80 per cent of queries in the UK - had lost some of its momentum.

Google said the results could be attributed to a series of quality initiatives, including an effort to reduce the number of times people clicked on a paid link accidentally and a reduction in the number of such links that appear overall.

Microsoft shares rose by 13 cents - or 0.46 per cent - to close at $28.31, while Yahoo!'s slipped 9 cents - or 0.33 per cent - to close at 27.07.