Following a board meeting late on Thursday afternoon, Vodafone said it was offering Mannesmann shareholders 240 euros per Mannesmann share in an all paper bid, raising an initial 203 euro per share bid that Mannesmann curtly rejected on Sunday.

Vodafone said it had received a letter from Mannesmann on Thursday urging it to withdraw its proposals and had consequently decided to put its case directly to shareholders of the German engineering and telecom companies.

"This is the only way we can present Mannesmann shareholders with the option of investing in the world's leading, international mobile telecommunications company," Vodafone chief executive Chris Gent said in a statement.

The headline price does not include Mannesmann's debt of around 23 billion euros, and banking sources said Vodafone wasseeking to raise a 23 billion pound ($37.2 billion) loan to help refinance these and its own 10.5 billion euro debt obligations.

Vodafone, which wants to win control over prized joint ventures in Germany and Italy, is hoping to use Mannesmann's supervisory board to help it win over the German company's management. Stung into action by the German group's $ 32 billion bid for its domestic rival Orange, the UK-based cellphone giant hopes to also make corporate history in Germany. The offer is expected to be rejected by the German company and set the scene for a high profile and bitter bid battle, Gent said.