WPP ceo Sir Martin Sorrell has lambasted media buying group Aegis and rival French advertising services conglomerate Havas.

A conference in Barcelona heard Sorrell accuse the two companies of "irrational" and "desperate" behaviour, a curious turn-of-phrase when he is mulling a bid for the former and will need the co-operation of the latter if he is to succeed.

He told the Morgan Stanley conference that Aegis's Carat and Havas's MPG units had guaranteed media rates to their clients, meaning their fees could be chipped away if the rate was not secured.

He described the strategy as "worrying" and "driven by people in the mid-market who are a bit worried about what the consolidators are doing".

MPG declined to comment but a spokesman for London-headquartered Aegis said: "As far as we are concerned, these comments are wrong and wide of the mark."

Sorrell refused to discuss his plans for an Aegis acquisition but he has until November 25 to decide whether to proceed with a bid. The company has a market value of £1.4 billion ($2.4bn; €2.05bn).

Havas chairman Vincent Bolloré has built up a near 25% stake in Aegis and will play a pivotal role in deciding its future.

Data sourced from Wall Street Journal Online; additional content by WARC staff