Kuwait will celebrate Liberation Day from Iraq in two weeks and Iraq still pays it reparations.
"Kuwait will earmark $1 billion in loans to Iraq and will commit to another $1 billion as investments", Emir Sheikh Sabah al-Ahmad al-Jaber al-Sabah said at the gathering.
Non-governmental organisations on Monday pledged $330mn but the main commitments are expected to be made by about 70 countries on the final day of the conference today.
UAE Minister of State for Foreign Affairs Anwar Gargash later tweeted that there were also $5.5 billion from the UAE in private investments in Iraq "in addition" to his country's pledge but it was not clear if this was a new announcement.
With the help of a US-led alliance, Iraq declared victory over "Islamic State" insurgency in December 2017, after its forces successfully reclaimed all the territory held by the extremist group.More news: Liverpool defeat Southampton and Twitter reacts to Reds win
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Iraq received promises of billions of dollars, mostly in credit facilities and investment pledges, on Wednesday from allies but has so far fallen short of the amount the government says is needed to recover from three years of war.
"If communities in Iraq and Syria can not return to normal life, we risk the return of conditions that allowed ISIS to take and control vast territory", he said, using an acronym to refer to the group. Only half of them have returned to their home towns. The US is not expected to make a direct government contribution at the conference, however.
Tillerson also vowed to allocate $200 million to support coalition's efforts against Daesh in Syria.
However, the secretary-general of Iraq's Council of Ministers Mahdi al-Alaq said nations could it help by acting as guarantors with global lenders.
The previous day, non-governmental organizations pledged $330 million of humanitarian aid to Iraq as worldwide donors gathered in Kuwait, KUNA reported.