French President Francois Hollande Reuters

(Reuters) - French President Francois Hollande said on Thursday that opposition forces fighting Islamic State militants in Syria and Iraq should have more Western support, but Syrian President Bashar al-Assad could not be an ally against jihadists.

"A large alliance is needed, but let's be clear. Assad is not a partner in the struggle against terrorism," he said in a speech.

Calling Assad an ally of the jihadists, he said. "There is no choice to be made between two barbarisms."

In a text provided before a speech to an annual conference of French ambassadors, Hollande also said: "To fight Islamic State, the international community must also arm opposition forces who are fighting it."

Syrian rebel forces have been fighting Assad for more than three years with political backing from the West in a war that has cost 190,000 lives.

However, the rise of hardline Islamist groups to the forefront of the struggle and their advances into neighboring Iraq has have posed a dilemma for Western policy.

France last week said it had provided weapons to the "moderate" Syrian opposition but diplomats have said there are differences of opinions between Paris and Washington on whether there should be more support in the future as efforts to fight Islamic State in Syria increase.

Hollande reiterated his plans for an international conference to help coordinate international action against Islamic State.

France would also increase its for Iraq, Hollande said.

"To fight Islamic State, the first condition is for Iraqis to unite," he said.

French diplomats have said they are hoping to hold the meeting, which include Iran, Arab states and the five permanent members of the U.N. Security Council, between Sept. 15-20.

Hollande also said there would be talks at the U.N. Security Council later this month to see how states across the world could prevent "young fanatics" from joining the ranks of the Islamic State.