As Israel is facing mounting pressure and condemnation over its deadly attack on a Gaza aid convoy, Turkey warns of cutting ties with Israel.

“Israel is faced with the danger of losing its sole friend in the region and the greatest contributor so far to regional peace,” Turkish Prime Minister Recep Tayyip Erdogan told US President Barack Obama in a one-hour telephone conversation.

“The steps that it (Israel) will undertake in the coming days will be determining for its position in the region,” the prime minister was quoted in a statement released by his office on Wednesday.

On Monday, Israeli naval commandos stormed the Gaza Freedom Flotilla, co-organized by the Turkish Humanitarian Relief Foundation, in international waters, killing around 20 people and wounding scores more.

Warning of “irreparable” damage to Turkish-Israeli ties, Ankara immediately condemned the attack on the convoy, recalled its ambassador from Tel Aviv and scrapped plans for joint military exercises with Israel.

Erdogan on Tuesday urged international sanctions against Israel, calling the move a “bloody massacre” and slamming Israel as “a festering boil in the Middle East that spreads hate and enmity, dynamites regional peace and spreads instability.”

In his telephone conversation with Obama, Erdogan condemned Israel’s attack on the aid campaign as “unacceptable lawlessness,” called for an end the blockade of Gaza and demanded that all activists held by Israel must be released.

Under sweeping outrage and escalating protests across the globe, Tel Aviv rushed to send home hundreds of activists it captured on the six-ship convoy, including dozens of Turkish nationals, saying the expulsions started late Tuesday and that all activists would leave within 48 hours.

“A first contingent of about 50 Turkish nationals arrested on board the Flotilla have left Beersheva prison by bus for Ben Gurion airport, from where they will be deported,” an Israeli official told AFP, adding more than 300 other Turkish nationals were yet to be released.