The head of Britain's Serious Fraud Office has asked his officials to look into allegations of irregularities in Vodafone's African dealings.

It is understood director Richard Alderman has instructed SFO investigators to gather intelligence surrounding Vodafone's £450million purchase of a majority stake in Ghana Telecom.

An official SFO investigation has not been launched.

However, Alderman is following the situation closely and may make contact with Vodafone's chief counsel in the coming days depending on his officials' findings, the Mail understands.

FTSE 100 giant Vodafone has been co-operating with an inquiry commissioned by the Ghanaian government into last year's deal with Ghana Telecom.

A report on the acquisition is due for publication, at which point Ghana's own Serious Fraud Office could become involved.

Purported extracts of the report have already been published in the Ghanaian press alleging that Vodafone underpaid for the stake and that the deal may have been unconstitutional.

Vodafone bought a 70 per cent stake in previously state-owned Ghana Telecom, as part of a strategy to expand into emerging markets, adding to interests it already had in Kenya, Egypt and South Africa.

But after taking office in January, Ghana's new government ordered a review, claiming the sale was 'fraught with irregularity'.

Vodafone is understood to welcome the prospect of an investigation by the Ghanaian SFO, which would allow the terms surrounding the acquisition to be thoroughly explored.

It denies any allegations of wrongdoing and has co- operated with the Ghanaian review.

However Ghana's government is currently thought to be preparing a statement that could clarify some of the issues raised in the review and take pressure off the UK mobile firm.

Last night a Vodafone spokesman said: 'We are awaiting a statement from the (Ghanaian) government.' The SFO declined to comment.