By Humeyra Pamuk
ISTANBUL (Reuters) - President Tayyip Erdogan said on Friday he would try to convince Donald Trump next month that Turkish-backed forces should be used to retake the Syrian city of Raqqa from Islamic State rather than Kurdish militia Ankara views as a terrorist threat.
Erdogan said Washington's support for Kurdish YPG fighters damaged "the spirit of solidarity" with Turkey, but that he believed a new page would be turned in ties under Trump, whom he will meet in mid-May for the first time he became president.
Turkey has long been annoyed by U.S. support for the YPG militia, seen by the Pentagon as a reliable partner in Syria but by Ankara as a hostile force linked to Kurdish PKK militants who have waged a three-decade insurgency against the Turkish state.
It is particularly frustrated by the use of YPG fighters in a planned U.S.-led offensive to retake Islamic State's Syrian stronghold of Raqqa on the northeast bank of the Euphrates river, an operation Ankara has long sought to join.
"Why are we asking for help from terrorist organisations? We are here," Erdogan said at an energy conference in Istanbul. "Turkey, coalition forces led by the United States and the Free Syrian Army all together can wipe them (Islamic State) out. This is not a difficult thing for us," he said.
"I believe we can achieve this and I will tell this to Trump."
Ankara fears creation of a contiguous Kurdish-controlled territory along its southern frontier that it believes could be used to support insurgency in Turkey and promote ambitions for a Kurdish state incorporating Turkish land. It aims to end all Kurdish military involvement west of the Euphrates.
Ties with Washington soured under former president Barack Obama and officials in Ankara have been hoping for an improvement under Trump.
"I am seeing signs that Trump...will display a more decisive stance in the fight against terrorism and in ending state terror in Syria," he said.
Washington has largely focused on defeating Islamic State, while Ankara has repeatedly said Syrian President Bashar al-Assad was the main reason for the six-year-old conflict and that he should be ousted.
Ties were further tested earlier this week when Turkish warplanes struck Kurdish targets in Iraq's Sinjar region and northeast Syria, regions Ankara described as 'terror hubs', killing about 70 inside the two neighbouring states.
The air strikes targeted the YPG but killed several members of the Iraqi Kurdish peshmerga by mistake and drew criticism from the United States which said it was given inadequate notice to ensure the safety of allied forces on the ground.
Erdogan said Turkey's southern border with Syria had come under intense mortar fire from YPG militia over the past two days but Ankara was responding.
"We will not allow efforts to create a terror corridor in our southern border," he said.
(Reporting by Humeyra Pamuk and Orhan Coskun; Writing by Dominic Evans; editing by Ralph Boulton)