Qatar Holding, which owns about 12% of Xstrata, had said it would block the merger as it wanted a ratio of 3.25.

BBC: Glencore tables fresh Xstrata bid

Qatar Holding, which owns about 12% of Xstrata, has said it wants an offer of 3.25 Glencore shares for every one Xstrata share.

BBC: Glencore confirms new Xstrata bid terms

Glencore had raised its offer after its first bid was opposed by key Xstrata shareholders, including Qatar Holding, the Gulf state's sovereign wealth fund.

BBC: Xstrata board backs Glencore merger

Xstrata shares had cooled off in recent months when its second-largest shareholder, Qatar Holding, pushed Glencore to hike its offer to 3.25 shares.

FORBES: Glencore Sweetens Bid To Save Xstrata Deal

Barclays says the UK's Serious Fraud Office has started an investigation into payments between the bank and Qatar Holding LLC, part of sovereign wealth fund Qatar Investment Authority.

BBC: Barclays faces SFO investigation

In August last year, the UK's Serious Fraud Office said it had started an investigation into commercial arrangements between the bank and Qatar Holding LLC, part of sovereign wealth fund Qatar Investment Authority.

BBC: Barclays misled shareholders about source of ?3bn

When Glencore had made its original offer of 2.8 Glencore shares for every one Xstrata share in February, Qatar Holding, which owns a 12% holding in Xstrata, had said that it wanted an offer of 3.25 shares.

BBC: Xstrata board backs Glencore merger