Yahoo! has begun testing its Panama advertising system in Britain, it has been revealed.

In an email on PPC Blog, the company claimed: "To help ensure we launch our new ranking model successfully we have started running a limited test across our UK advertiser listings in which the display order of sponsored search listings in some keyword markets is based on factors other than bid."

The paid search facility aims to help online marketers target users with advertisements more catered towards their interests.

Meanwhile, the search engine company advised online advertisers to track their paid search campaigns from "individual keywords, so that you can manage your bids and creative for maximum return-on-investment".

Panama is set for mainstream launch "soon", beginning with advertiser migration which is reported to take place before July.

Last month, a report by TravelMole indicated that the company could combine audio clips, videos and pictures into its text search results.