The EU will work with the State of Kuwait to strengthen support for Iraq in this critical time, stressing that the Union is keen to work with Kuwait in order to promote stability and prosperity in Iraq, Mogherini added.
Guterres said 2.5 million remain displaced in the aftermath of the devastating war in Iraq.
Dr Anwar Gargash, UAE minister of state for foreign affairs, announced the United Arab Emirates would pledge $500 million.
Some would be turnkey projects, in which contractors would hand over facilities to Iraq, while others would be build-operate-transfer deals in which private firms would receive concessions to operate facilities.
The announcement Wednesday falls short of the $88.2 billion requested by Iraq, however it is far higher than the amount previously announced by those taking part.
The Qatari Minister of Foreign Affairs, Sheikh Mahmoud Bin Abdulrahman Al Thani, also said that his country is committed to supporting reconstruction of Iraq, pledging around $1 billion.
The Islamic Development Bank also pledged $500 million toward reconstruction in Iraq.
Kuwait will earmark $1 billion in loans and another $1 billion in direct investments to neighboring Iraq, the country's emir announced Wednesday.
Saudi Arabia and Qatar also said they would allocate $1.5 billion and $1 billion, respectively.
Iraq aims to secure investments worth $100 billion to rebuild its infrastructure after a three-year war against ISIS.
Kuwait's offer by the country's ruling emir, Sheikh Sabah Al Ahmad Al Sabah, shows the deep interest his nation has in making sure Iraq becomes a peaceful, stable country after the war against the Islamic State group and the chaos that followed the 2003 US-led invasion of Baghdad. The move is seen as a stunning donation as only a generation ago Saddam Hussein invaded the small, oil-rich nation, AP said. Saddam was later toppled by the 2003 USA invasion.