Poland investigates further cases of railway disruptions

WARSAW (Reuters) - Unauthorised use of an emergency radio system on Poland's railway caused 25 trains in four regions to be stopped on Tuesday, intensifying a disruption on a network that has seen a series of incidents in recent days that are being investigated by authorities.

Radio-stop signals allow trains to be halted remotely, and there have been several incidents of unauthorised use of the system in recent days. On Sunday, two men, one of whom was a serving police officer, were arrested in the eastern city of Bialystok over the unauthorised use of radio-stop signals, according to news agency PAP, citing a court press office.

"Today as of 13:00 p.m. on the railway network in Poland, the unauthorized use of the radio stop signal was recorded in the Lodzkie, Mazowieckie, Opolskie and Pomorskie regions," PKP PLK railway operator said in a statement.

The company said the radio-stop system was not part of rail traffic control and radio communication devices were not able to affect the operation of traffic control devices, so unauthorized use of the system did not affect railway safety.

It added authorities were investigating the incident.

"There was no danger to passengers," PKP PLK said. "As a result of the unauthorized use of the radio stop signal, a total of 25 trains were stopped ... All cases have been reported to the relevant authorities whose task is to establish the circumstances."

"The internal Security Agency is conducting explanatory proceedings in connection with a series of incidents destabilizing part of railway traffic in Poland," said Stanislaw Zaryn, deputy coordinator of special services.

On Saturday, he said the Internal Security Agency (ABW) and police were probing unauthorized use of the system involved in rail traffic management in northwestern Poland.

Separately, the state railway operator is investigating the derailment of two trains and collision of another two on Thursday.

(Reporting by Alan Charlish and Anna Wlodarczak-Semczuk; Editing by Bernadette Baum)