Turkish President Recep Tayyip Erdogan said Thursday that U.S. State Secretary John Kerry intends to visit this month, in what would be the first trip by a top Western dignitary since a failed putsch.

Kerry's visit, if confirmed, comes at a time of heightened tensions between Washington and Ankara in the wake of the attempted military takeover on July 15.

President Recep Tayyip Erdogan on Saturday said he wanted to introduce constitutional changes to bring the Turkish spy agency and military chief of staff directly under his control as he seeks to tighten his grip on the country after the failed coup.

Turkish President Recep Tayyip Erdogan will visit Russia on August 9 for his first face-to-face meeting with Vladimir Putin since Moscow and Ankara mended ties damaged by the downing of a Russian jet last year, Turkish officials said Tuesday.

Turkish President Recep Tayyip Erdogan on Monday accused the EU of not paying its way under a deal to send Syrian refugees back across the Aegean.

The Kremlin confirmed on Wednesday that Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan plan to meet in Russia in early August.

Recep Tayyip Erdogan, who appears to have survived a bloody attempt to remove him from power, is the most divisive leader in the history of the modern Turkish republic.

Adored by supporters as a transformative figure who modernised Turkey, his foes paint him as an increasingly despotic "Sultan" who ruthlessly shuts down any criticism.

President Barack Obama on Wednesday offered US security assistance to Turkey after 41 people were killed in a suicide assault on Istanbul airport, the latest in a string of attacks to rock the US ally.

Obama telephoned President Recep Tayyip Erdogan "to express his deep condolences on behalf of the American people," White House spokesman Josh Earnest told reporters traveling with the US leader to a summit in Ottawa.

President Vladimir Putin on Wednesday lifted restrictions on travel to Turkey after mending ties with his Turkish counterpart Recep Tayyip Erdogan, seven months after Ankara downed a Russian jet, triggering a raft of sanctions.

Russian President Vladimir Putin is to hold his first phone call with Turkish counterpart Recep Tayyip Erdogan since Ankara downed one of Moscow's warplanes in Syria, the Kremlin said Tuesday.

The Kremlin said Monday that Turkish President Recep Tayyip Erdogan had apologized to his Russian counterpart Vladimir Putin over Ankara's downing of one of Moscow's military jets in Syria last year that shattered ties.

Putin has repeatedly demanded an apology from Erdogan since the November 24 incident and the latest move could help spell the end of a feud that has seen Moscow slap a raft of sanctions on Ankara.