Qatar's Sheikh Jassim bin Hamad al-Thani made an improved final offer for Manchester United in an attempt to see off his main rival British petrochemicals billionaire Sir Jim Ratcliffe, The Times reported on Tuesday.

Sheikh Jassim is offering to buy 100 per cent of the club now for a price nearer to £5 billion ($6.31 billion), the report said. Manchester United's shares were up 1.2 per cent.

Sheikh Jassim's offer falls short of the £6 billion asking price set by current owners, the Glazer family, The Guardian reported in April.

United's American owners late last year launched a formal sale process and have received several bids, including from British billionaire Jim Ratcliffe, founder of chemicals producer INEOS, and Finnish businessman Thomas Zilliacus.

According to a report by The Times, Ratcliffe's INEOS had outbid Sheikh Jassim in the battle to buy United.