Yahoo has launched a new search engine that aims to deliver more relevant results.

The oneSearch service offers results from a number of sources, combining web pages with videos and images.

Users hesitating when they enter a search query will be presented with a list of suggested search terms, allowing them to better define their query.

A search for 'Windows Vista', for instance, can be expanded with words like 'themes', 'download' or 'productivity'.

Yahoo launched oneSearch for mobile phones in March, allowing users quickly to narrow down a search with a minimum number of clicks.

Google was quick to catch up, releasing its Universal Search in May spanning web, local, video and image search.

Google also started incorporating an automatic spell checker, adding correctly spelled results without prompting the user.

The move towards unified search comes after search firms expanded their offerings with specialised services that index only one medium, such as photos, blog postings or news reports.

Unifying the results acknowledges that users often do not know exactly what they are looking for, and are therefore unable to formulate the best query.

Yahoo announced yesterday that oneSearch will be the main search service on Telefónica's mobile portals in 15 countries in Europe and Latin America.