Germany’s HeidelbergCement has attempted to shut out any rivals for its £8 billion takeover of Hanson by mounting a dawn raid that increased its controlling stake in the London-quoted building materials company to more than 29 per cent.

Traders at Deutsche Bank spent £1.4 billion buying 125.63 million Hanson shares in the open market at 1,100p, level with the recommended cash offer agreed on Tuesday and raising its direct holding to 27.7 per cent from 10.06 per cent.

With a 2.2 per cent Hanson shareholding owned by the Merckle family – HeidelbergCement’s controlling shareholders own more than 80 per cent of the company – the Germans now own or control nearly 29.9 per cent.

Alan Murray, chief executive of Hanson, has said that his company has not received approaches from any third parties, but there has been speculation that rival cement-makers such as Cemex or Lafarge could muscle in and break up the merger with Heidelberg.

Dr Berndt Sheifele, chief executive of Hanson, has offered Mr Murray a role in the enlarged group as head of US and Asia Pacific, a job he is likely to accept, according to sources.

Mr Murray, 53, ran Hanson’s Australian arm for seven years and then its US business between 1998 and 2002 before becoming group chief executive. He told The Times: “It is an opportunity that is of interest, but discussions are not that far down the line . . . I like the business. It has not been a hard sell from that point of view.”

Meanwhile, Hanson is suing its former lawyers for alleged negligence over advice they gave on a property deal with Manchester United.

The company has issued a High Court claim for £691,000 against Nabarro, a leading City law firm.

The cement-maker alleges that, while trying to terminate a property deal with the football club, it suffered financial loss as a direct result of shoddy advice given by Nabarro.

A spokesman for Nabarro confirmed that the firm had received the claim and that it would defend itself.

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