WARSAW, Poland — The Croatian military police have launched a probe into the Defence Ministry's acquisition of 12 modernized Mikoyan MiG-21 fighter jets from Ukraine.

The development comes amid suspicions of bribery and claims that the supplied aircraft are not fit to be operated and do not comply with the technical documentation, local daily Jutarnji List reported.

Following a deal signed by the Croatian Defence Ministry and Ukraine's state-run arms exporter Ukrspecexport in July 2013, the company was to supply used Soviet-designed fighter jets that were previously operated by Jordan. The 12 aircraft were delivered to Croatia by July 2015, but five fighters were subsequently withdrawn from service for technical reasons.

An investigation by the Croatian military police has shown that the upgraded fighters contained old parts acquired from Bulgaria, Algeria and the former Soviet Union that did not match the technical documentation supplied by the Ukrainian company. In addition to this, the Yemeni Air Force has claimed that five of the procured fighter jets were in fact property of the country's military.

Meanwhile, the Croatian government is considering whether to purchase new fighter jets and replace its Soviet-built aircraft. The plan was unveiled last year following a meeting between Croatian President Kolinda Grabar-Kitarovic and Prime Minister Zoran Milanovic.

The two leading contenders for the designed deal reportedly include Lockheed Martin's F-16 and Saab's JAS-39 Gripen, with considered alternatives comprising the French Mirage, Israel's Kfir and a variant of South Korea's T-50.

Jaroslaw Adamowski is the Poland correspondent for Defense News.

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