The United Arab Emirates' official news agency says the country's ruler has pledged four billion dollars to boost Egypt's economy.

WAM reported Friday that Sheikh Khalifa bin Zayed Al Nahyan has ordered two billion dollars of investment in Egypt, and will deposit two billion dollars in the Egyptian central bank to increase its foreign reserves.

The announcement comes a day after Abu Dhabi's crown prince Mohammed bin Zayed Al Nahyan visited Egypt.

The UAE has been one of the main backers of Egyptian President Abdel-Fatah el-Sissi after he led the overthrow of the country's Islamist president in 2013.

Egypt's economy is suffering following a slump in its vital tourism sector and a devaluation of its currency, and the government faces growing international criticism over its poor human rights record.