A U.N. panel aimed to prevent torture says it's cutting short a trip to Ukraine because security forces aren't granting access to sites that it wants to visit.

Envoys from the U.N. Subcommittee on Prevention of Torture say the denial of access by the Ukrainian Security Service, SBU, violates Ukraine's own international commitments.

Delegation chief Malcolm Evans says the four-member team was unable to visit "some places where we have heard numerous and serious allegations that people have been detained and where torture or ill-treatment may have occurred."

The U.N. human rights office said Wednesday that the visit began May 19 and was to end Thursday.

The suspension in mid-mission was only the second ever by that subcommittee, which has conducted over 40 missions since its creation in 2007.