Mr Gent said he was preparing a direct appeal to Klaus Esser this week to discuss what is the world's largest takeover offer. But the Mannesmann chairman snubbed the approach, saying there was no point in talks unless Vodafone sweetened its all-paper offer.
The rejection sets the stage for the formal commencement of hostilities between the pair, with the posting of Vodafone's offer document to the German company's shareholders expected before Christmas.
A Mannesmann spokesman said the company was expecting notification of a legal challenge to its board's rejection of the Vodafone bid, launched by a group of Mannesmann shareholders.
Mr Esser said: "With the Vodafone offer being final, it is difficult to see the potential in further talks.
"There is no strategic incentive for Mannesmann to combine with Vodafone, nor has Vodafone offered adequate financial incentive to compensate Mannesmann shareholders for taking paper in a company with significantly lower growth prospects."
The sparring is the latest stage in an increasingly bitter struggle between the companies for the lead role in shaping telecoms provision across Europe. It is the first hostile bid for a German company by a foreign rival. Last month Vodafone raised its initial 203-euro-a-share bid to about 240 euros. The subsequent rise in Vodafone shares places its offer value at about 260 euros a share.
Before the Mannesmann rejection, a Vodafone official said Mr Gent would make a personal plea to Mr Esser. "Vodafone has always tried to do this on a friendly basis," the spokesman said. "Mr Gent will be putting in a call [to Mr Esser] this week."
It was unclear last night whether Mr Gent would press on with his executive- to-executive lobbying.
German weekend newspapers said Mannesmann faces legal action from some shareholders, angry at the board's rejection of Vodafone. A company official said Mannesmann had not received formal notification of the challenge.
Several Hamburg shareholders filed a court injunction against Mannesmann in the Dusseldorf district court on Friday on the grounds that the management was acting against shareholders' interests, Welt am Sonntag reported. The complaint argues that Mr Esser's defence is illegitimate because German company law demands that the management of Mannesmann maintains a neutral stance.
Andreas Dimke, the lawyer heading the action, said: "The management board of Mannesmann is evidently not aware that it is merely an administrator for the shareholders."
There was no indication how many shareholders Mr Dimke represents, nor the scale of their shareholdings.