PREVIEW-Turkey to host Sudan, Iran leaders at summit

* Bashir, Ahmadinejad to attend OIC meeting

* ICC arrest warrant, nuclear row could overshadow gathering

* Host Turkey's foreign policy fuels Western worries

By Thomas Grove

ISTANBUL, Nov 6 (Reuters) - A summit of Islamic countries in Istanbul next week will boost Turkey's quest to deepen ties with the Muslim world, but some of its new friends are not to the taste of its traditional ally, Washington.

Sudan's President Omar Hassan al-Bashir, who has an international arrest warrant against him for war crimes, and Iran's Mahmoud Ahmadinejad, engaged in a standoff with the West over Tehran's nuclear programme, are among leaders who will attend an Organisation of the Islamic Conference (OIC) meeting.

The one-day summit on Monday will add to growing concerns in some Western circles that Turkey, an OIC member which is seeking European Union membership, is shifting away from its pro-Western foreign policy and embracing countries such as Iran and Syria, while distancing itself from regional friend Israel.

"I think this summit will put Turkey again on the frontline, both in regards with Iran and Bashir," said Hugh Pope, a senior analyst for the International Crisis Group.