Erdogan and Obama
Turkish Prime Minister Recep Tayyip Erdogan (L) listens to President Barack Obama as they address a joint news conference at the White House - Reuters

President Barack Obama and Turkish Prime Minister Recep Tayyip Erdogan have reiterated that Syrian President Bashar al-Assad must step down amid the spiralling crisis in the region.

The two leaders, who met at the White House to discuss the ongoing Syrian civil war, emphasised that Assad's departure is the only solution to the conflict.

"We're going to keep increasing the pressure on the Assad regime and working with the Syrian opposition. We both agree that Assad needs to go," said Obama, adding that Turkey has a crucial role to play in the region.

The meeting between the leaders lasted for nearly two hours. Syria was on top of their agenda during the discussions and both the leaders agreed that use of chemical weapons is a red line.

Obama continued: "There are a whole range of options that the United States is already engaged in. And I preserve the options of taking additional steps, both diplomatic and military, because those chemical weapons inside of Syria also threaten our security over the long term as well as our allies and friends and neighbours."

The US president also offered his condolences for the victims of the recent attack on the Turkish-Syrian border which killed dozens of people. Turkey suspect's Assad hand in the attack, but Syria denies the caim.

Erdogan said the discussions with Obama were a milestone in US-Turkey relations.

"During the talks we saw that our thoughts on the process until today and on what can be done from now on overlapped," said Erdogan.

He said Turkey would work with the UN and the Arab League to find a solution.

"I want to see the glass half full. We want to see the sensibility of the international community. I believe that the United States is showing efforts [in Syria]. We will work to [find a quicker solution] with members of the UN Security Council, of the Arab League or other countries who show their sensibility even if they are outside [the region]."

Erdogan is expected to meet other top American leaders including Vice President Joe Biden and Secretary of State John Kerry later in the day to discuss Syria.