Havas chairman Vincent Bolloré is still manoeuvring to force an unwelcome alliance on UK market research and media group Aegis.

Speaking at the Cannes Lions International Advertising Festival, he told the massed ranks of industry press that "all doors were open" on the question of raising his 29% stake in Aegis to the 30% threshold where UK law would require him to launch a takeover bid.

He was also unbowed by defeat two weeks ago at the Aegis annual meeting when he failed to get two nominees voted on to the company's board.

He intimated that he would call an extraordinary meeting of shareholders in September, to attempt the board ascent again in more favourable conditions.

Bolloré's stated aim is to team with Aegis to compete more successfully with rivals such as Omnicom and WPP Group.

He told journalists: "We will be persistent. It is a strategic investment for us and I believe there are synergies between Havas and Aegis. The best way is for Aegis to remain independent. It is more motivating than selling to a big player."

Aegis chairman Lord Colin Sharman is vociferous in his opposition to Bolloré's perceived predations and believes his interest in Havas, the Paris-headquartered advertising holding group, is a conflict of interest.

Data sourced from MediaGuardian.co.uk; additional content by WARC staff