Saudi Arabia is one of the main backers of the insurgency against Syrian President Bashar al-Assad.

Ahmed Jarba, head of the opposition National Coalition, met with Saudi Crown Prince Salman bin Abdulaziz and Foreign Minister Prince Saud al-Faisal on Tuesday.

"The talks focused on continuing the Saudi aid and on the need to strengthen the capacities of the Free Syrian Army (FSA)," Jarba's advisor Monzer Aqbiq told AFP on Wednesday.

More aid is needed "to face the increasing number of mercenaries and militias belonging to (Lebanese movement) Hezbollah and Iraqis" fighting alongside the Syrian government, he said.

The FSA is also "battling extremists from the Islamic State of Iraq and the Levant (ISIL), who serve the regime's interests," claimed Aqbiq.

Jarba told Prince Salman during their meeting that the government's announcement of a June 3 presidential election has "closed the door to any political solution," according to a statement by the Coalition.

Arab Spring-inspired demonstrations against Assad erupted in March 2011 and later escalated into a foreign-backed armed insurgency.

The June vote will be the first presidential election organized by the government after constitutional amendments did away with the previous referendum system.

Syria has been gripped by deadly unrest since 2011. According to reports, Western powers and their regional allies -- especially Qatar, Saudi Arabia, and Turkey -- are supporting militants operating inside the country.

More than 150,000 people have reportedly been killed and millions displaced so far due to the turmoil in the country.

HH/HH