A swan mourning the death of its companion on a German railway track held up 23 trains for almost an hour and had to be removed by firefighters using special equipment, police said.

The two birds had strayed onto the track area of the high-speed line between Kassel and Gottingen in central Germany "during an excursion", according to Kassel police.

One of the birds died, likely after getting caught in the overhead power cables, said the statement on the December 23 incident, which was made public Monday.

Its companion then sat beside the body in mourning, resisting attempts by officials to lure it away and temporarily closing the line to traffic.

According to Britain's Royal Society for the Protection of Birds, swans try to find a mate for life
According to Britain's Royal Society for the Protection of Birds, swans try to find a mate for life AFP / Christof STACHE

Firefighters with special equipment were later called in and managed to lift the dead swan and its surviving companion away from the area.

Twenty-three trains were delayed for about 50 minutes while the rescue operation took place, the police statement said.

The surviving swan was unharmed and later released onto the river Fulda, it added.

According to Britain's Royal Society for the Protection of Birds, swans try to find a mate for life.