Ten Arab states, including heavyweight Saudi Arabia, agreed Thursday in Jeddah to rally behind Washington in the fight against Islamic State jihadists, as it seeks to build an international coalition.
"The participating states agreed to do their share in the comprehensive fight" against IS, said a statement at the conclusion of a meeting between US Secretary of State John Kerry and his Arab counterparts.
In addition to Saudi Arabia, the other Arab states are Bahrain, Egypt, Iraq, Jordan, Kuwait, Lebanon, Oman, Qatar and the United Arab Emirates.
Although Turkey was represented in the meeting, it was not mentioned in the final communique and a Turkish government official said Ankara has refused to take part in combat against the militants.
Kerry is to fly on Friday to Ankara for urgent talks with officials in Washington's key ally.
The United States has pressed Arab nations to join a coalition aimed at supporting the US campaign against the jihadists.
In the final statement, the 10 countries and Washington declared their "shared commitment to stand united against the threat posed by all terrorism, including the so-called Islamic State in Iraq and the Levant".
Participation in the fight will include "as appropriate, joining in the many aspects of a coordinated military campaign against ISIL", said the statement.
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The fight will include "stopping the flow of foreign fighters through neighbouring countries, countering financing of ISIL and other violent extremists, repudiating their hateful ideology, ending impunity and bringing perpetrators to justice".
It will also include "contributing to humanitarian relief efforts, assisting with the reconstruction and rehabilitation of communities brutalised by ISIL, supporting states that face the most acute ISIL threat".
Kerry told reporters that Arab partners will play a "leading role" in the coalition.
"As I understand(...) from the meeting we had today, Arab nations play a critical role in that coalition, a leading role," he said.
A US official in Jeddah said Turkey had its reasons for staying out of the coalition.
"We understand the challenging situation Turkey is in given their detained diplomats and they will make the decision on what role they can play moving forward."
IS militants hold 49 Turks hostage, including diplomats and children, abducted from the Turkish consulate in Mosul in Iraq on June 11.
"Turkey remains an important partner on counterterrorism and we will continue to consult closely as we work together to address the threat from ISIL," the official said.
Saudi Foreign Minister Prince Saud al-Faisal called for a "comprehensive approach" that does not focus on one country in the fight against "terrorism", citing Iraq, Lebanon, Libya, Syria and Yemen as affected countries.