Turkish police detained four Islamic State group suspects who were allegedly planning to carry out a "sensational" attack in Turkey and seized 24 suicide attack belts, officials said Thursday.

The latest detentions came as CIA chief Mike Pompeo arrived in Turkey to discuss the fight against the extremist group in Syria and Iraq, making his first overseas trip since taking office.

Police found the suicide belts — made with 150 kilograms (330 pounds) of explosives and fortified with metal pieces — as well as two automatic rifles, 14 kilograms (31 pounds) of TNT, cellphones that could be used as detonators and other materials during an anti-terror operation in Gaziantep, near the border with Syria.

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There were no details on the nationalities of the suspects, who were allegedly taking orders from high-level IS members in Syria. One suspect was wanted for membership in a terror organization, according to the Gaziantep provincial governor's office.

The suspects were being questioned by prosecutors Thursday, an official at the governor's office said. He said the four led police investigators to a field and other locations where the explosives and other material were hidden.

The official spoke on condition of anonymity in line with government regulations that bar civil servants from speaking to journalists without prior authorization.

Video of the operation provided by the governor's office showed a sniffer dog with a handler in a field and officials unearthing various explosives and other objects. In another shot, an official is seen removing an automatic weapon, wrapped in plastic, from what appeared to be a gap on the side of a building.

Last year, Turkey suffered a series of deadly attacks carried out by IS or Kurdish militants and has stepped up anti-terrorism operations across the country. Some 750 people with alleged IS links were detained in a major police sweep in 29 Turkish provinces last week.

Pompeo met with his Turkish counterpart, Hakan Fidan, and the two later held discussions with President Recep Tayyip Erdogan, the Turkish leader's office said, without providing details.

The talks were to include plans for a possible operation to retake the Islamic State group stronghold of Raqqa, a security official, who spoke on condition of anonymity in line with government regulations, told The Associated Press.

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Pompeo's visit follows a phone call between President Donald Trump and Erdogan.

Turkey is hoping for a reset in relations with the U.S. that were strained under the Obama administration over Turkish demands for the extradition of a U.S-based cleric, Fethullah Gulen, who Turkey has accused of orchestrating a failed coup.

Turkey was also angered by U.S. backing for Syrian Kurdish fighters, since it considers them terrorists because of their links to outlawed Kurdish rebels in Turkey.

Turkey, which has troops currently trying to liberate the IS-held town of al Bab in Syria, is pressing for a joint operation with the U.S. to re-capture Raqqa without the Syrian Kurdish groups' involvement.

The security official said during talks with Pompeo, Turkey would also seek greater U.S. co-operation in Turkey's struggle against Gulen's movement and the Kurdish rebels.