The International Tribunal for the Law of the Sea will hear the case of the three Ukrainian Navy ships seized when Russia blocked entry to the Azov Sea with a tanker late last year.

The Hamburg-based, UN-backed body will hold hearings on 10 and 11 May, it announced Wednesday.

On 16 April, Ukraine asked the tribunal to step in, alleging Russia had violated the sovereign immunity afforded to navy ships and their crews under the UN Convention of the Law of the Sea when Russia detained the Berdyansk, the Nikopol, the Yani Kapu and two...