Search marketing commentators in the US are speculating that the planned tie-up between Google and Yahoo may be about to come to a premature end. The deal, agreed in principal several months ago, was brokered by the two search engines and would see Google pay per click adverts appearing at the side of Yahoo search results. More about PPC Ad Deal

Since announcing the collaboration, the two platforms have come under increasing scrutiny from US competition regulators. The search engines met with the US Department of Justice yesterday, the latest in a series of meeting since the June ceasefire.

Unless agreements can be reached with the advertising bodies and competition watchdogs, it is possible the deal will be scrapped. Both Google and Yahoo have denied this is on the cards with Yahoo stating that the use of Google AdWords ads in their search results will drive a better marketplace for its users and advertisers. The collaboration with Google also fires a strong cease and desist warning to Microsoft, who has made a number of bids to oust the current Yahoo board and take over its search rival.

For their part, Google declared that the agreement is beneficial to search competition. According to stats from ComScore the two search engines dealt with 80% of all US search queries in July.