UPDATE 1-Turkey says all its observation posts in Syria will remain in place, support to continue

(Adds U.S. military statement)

ANKARA, Aug 21 (Reuters) - All of Turkey's observation posts, formed under an agreement with Russia and Iran, will remain in place and support will continue to be provided to the posts, Turkish presidential spokesman Ibrahim Kalin said on Wednesday.

On Monday, a suspected Syrian army strike hit near a Turkish military convoy heading to an observation post near Idlib's Khan Sheikhoun. Damascus denounced what it said was a Turkish attempt to save routed rebels.

Speaking to reporters after a cabinet meeting, Kalin said President Tayyip Erdogan would hold phone calls with Russian President Vladimir Putin and U.S. President Donald Trump in the coming days to discuss developments in Syria.

He said a schedule agreed upon with the United State for the planned safe zone in the east of the Euphrates in Syria will be gradually implemented in the coming weeks, adding that Turkish and U.S. troops will begin joint patrols in the region soon.

In Washington, the Pentagon said U.S. Defense Secretary Mark Esper spoke with his Turkish counterpart on Wednesday and that the security mechanism in northeast Syria would be executed in "designated phases."

Esper and Turkish Defense Minister Hulusi Akar "confirmed their intent to take immediate, coordinated steps to implement the framework as demonstrated by standing up the Joint Coordination Center in Turkey," the Pentagon statement said. (Reporting by Ezgi Erkoyun and Tuvan Gumrukcu; Additional reporting by Idrees Ali in Washington; Editing by Lisa Shumaker)