US Secretary of State John Kerry said Sunday he had asked Turkish Prime Minister Recep Tayyip Erdogan to delay a visit to the Gaza Strip planned for next month, as he pushes for improved Israeli-Turkish ties.

"We have expressed to the prime minister that it would be better to delay," Kerry told reporters in Istanbul, urging Erdogan to wait for the "right conditions".

"We thought the timing is really critical," Kerry added without elaborating.

Erdogan announced last week he planned to visit the impoverished Palestinian territory at the end of next month after a key trip to Washington on May 16.

Erdogan, a staunch advocate of the Palestinian cause, had earlier planned to visit Gaza this month to help the process of lifting an Israeli embargo.

That trip was also reportedly delayed after a warning from Washington, which last month brokered a rapprochement between Turkey and Israel.

Israel in March apologised for the deaths of nine Turks during a 2010 raid on a Gaza-bound aid flotilla which had wrecked ties between the former allies.

But for full normalisation, Ankara insists Israel lift its restrictions on Gaza and pay compensation for the flotilla victims, an issue to be discussed in Ankara with a visiting Israeli team on Monday.