Turkey "expects" the Trump administration to grant it waivers from U.S. sanctions related to its purchases of Iranian oil and Russian air defenses, a top aide to Turkish President Recep Tayyip Erdogan said Tuesday.

Presidential spokesman and senior adviser Ibrahim Kalin told a news conference he couldn't be certain that the waivers would be granted. But, he said Turkey had made a strong case that should be heeded.

Turkish Defense Minister Hulusi Akar held unannounced talks with acting Pentagon chief Patrick Shanahan Tuesday amid tensions over Ankara's plans to buy a Russian missile defense system and its threat to attack Kurdish fighters in Syria.

President Recep Tayyip Erdogan said the delivery of Turkey's disputed Russian S-400 missile defence systems could be earlier than initially planned, Hurriyet daily reported on Wednesday.

Ankara's purchase of the S-400s risks US sanctions and has further strained already tense relations with Washington.

Turkey's Supreme Electoral Council rejected a demand from President Recep Tayyip Erdogan's party for a recount of all ballots cast in Istanbul in last week's election, the party's deputy chairman said on Tuesday.

The ruling Justice and Development Party (AKP) challenged the results of Istanbul's March 31 mayoral ballot after their candidate Binali Yildirim narrowly lost against the main opposition CHP's Ekrem Imamoglu.

Soon after his ruling party faced defeat in Ankara and Istanbul in last Sunday's election, Turkish President Recep Tayyip Erdogan was quick to promise reforms to revive the country's weakened economy.

Turkey's opposition candidate for Istanbul mayor Ekrem Imamoglu said Friday he was still winning by nearly 19,000 votes after the ruling AKP demanded a recount following Sunday's tight election race.

US Secretary of State Mike Pompeo warned Wednesday of "devastating" results if Turkey strikes Syria as he met in Washington with Foreign Minister Mevlut Cavusoglu.

The United States said Monday it was halting all deliveries and joint work with Turkey on the F-35 fighter jet program after the NATO ally insisted on a major arms purchase from Russia.

Turkey's government on Friday rejected US pressure over its disputed deal to purchase Russian missiles, saying Ankara was already in talks over delivery of the S-400 defence system.

A U.S. consulate staffer went on trial in a Turkish court on Tuesday accused of spying and attempting to overthrow the government in a case that fuelled tensions between the United States and its NATO ally.

Metin Topuz, a Turkish citizen and long-time liaison with the US Drug Enforcement Administration, was arrested in 2017 accused of ties to US-based preacher Fethullah Gulen who Ankara says ordered a failed 2016 coup.