Pro-Russian separatist rebels in eastern Ukraine on Saturday released a second group of four monitors from the Organization for Security and Cooperation in Europe (OSCE), who had been seized on May 29, a Reuters witness said.

A Reuters correspondent saw the four - three men and a woman - driven by heavily armed men up to the entrance of a hotel in the eastern city of Donetsk.

They stepped out, shook hands with other waiting OSCE representatives and then went into the hotel.

A first group of OSCE monitors, detained days earlier by pro-Russian separatists, had been released in the early hours of Friday.

(Reporting by Aleksandar Vasovic, writing by Richard Balmforth; Editing by Kevin Liffey)

(Reuters) -