The Swiss air traffic controller who was on duty when two planes collided over Germany earlier this month has issued a statement of condolence to the families of the 71 people killed. He issued the statement to Swiss media through his lawyer.

In the statement, the unidentified Swiss air traffic controller expressed his grief at the deaths, and extended his sympathy to the families, who have suffered, what he called, irreplaceable losses.

He acknowledged that errors in the traffic control system contributed to the disaster. He said he was part of a network of people, computers, surveillance and transmission instruments, which must work seamlessly and without error.

Among the victims were 45 Russian children who were on a holiday trip to Spain. A funeral service for the children was held on Saturday in the Russian town of Ufa in the Ural mountains.

Switzerland's president, Kaspar Villager, canceled plans to attend the memorial service, after Russian authorities told him that people were angry and he would not be welcome.

Preliminary investigations into the crash show that, on the night of the accident, the Swiss controller was monitoring two radar screens and two radio frequencies alone. His partner was on a break. At the same time, Swiss controllers said their collision alert system was out of action. Also, they said their telephones were not working, so German colleagues were not able to warn them. The Swiss controller, who was suspended from work, reportedly went into shock after the collision. In his statement, the controller said he has been cooperating fully with German officials leading the investigation.