Manchester United have received a second Qatari bid to buy the English football giants, British media reported on Saturday.

The Press Association and the Guardian, among others, said Sheikh Jassim Bin Hamad Bin Jassim Bin Jaber AI Thani, the chairman of Qatar Islamic Bank, had placed a second round offer overnight.

British billionaire Jim Ratcliffe made a revised bid on Thursday as Finnish entrepreneur Thomas Zilliacus entered the race to own the Old Trafford club.

Bidders were initially told they had until 9pm GMT on Wednesday to submit new offers, but reports say that has been extended.

No figures have been revealed but one or more of the initial bids were understood to be in the region of £4.5 billion.

That would make Manchester United – who have not won the Premier League for a decade – the most expensive sporting club in history, although it would be short of the £6 billion valuation reportedly placed on United by its current US-based owners, the Glazer family.

Sheikh Jassim and Ratcliffe, the founder of chemicals giant INEOS, remain the front runners to buy United should the Glazers give up control of the club.

Zilliacus entered the race on Thursday, with a bid he said will give fans the chance to own 50 percent of the club.

"My bid is built on equality with the fans," Zilliacus, founder and chairman of investment company Mobile FutureWorks, said in a statement.

The Glazers have angered many United supporters by saddling the club with huge debts since they took over in 2005. They appeared ready to cash out at an enormous profit when they invited external investment in November.

However, they could yet shun the option of selling a controlling stake in the club, with other parties understood to be interested in a minority shareholding.

The Times reported US hedge fund Elliott Investment Management, which sold AC Milan for $1.3 billion last year, has made a bid for a minority stake.

A first round of bidding took place last month and it has been reported there are as many as eight separate potential investors in the club. (AFP)