A section of Vladimir Putin’s new bridge linking Russia to the annexed Ukrainian peninsula of Crimea plunged into the water as it was being put in place.
The blunder means work on the highly controversial Kerch railway bridge, the longest in Europe, has been halted.
It will take a month to repair the damage and install a new section, according to Kremlin-controlled news website Ria Novosti.
It reported that the segment collapsed over open water between the Tuzla Split and Tuzla Island on Thursday and no one was injured.
The planned December 2019 opening of the railway bridge is not expected to be delayed, Ria Novosti said.
The Russians finished the road part of the bridge in May of this year, with Putin opening the link by leading a convoy of trucks across it during the opening ceremony.
The opening ceremony had seen a massive security effort spearheaded by the Russian FSB security service, amid fears of attacks from Ukrainian nationalists.
Putin boasted that the 12-mile crossing was a dream of both the Russian Tsars and Communist leader Joseph Stalin, but has only happened under his rule.
The road towards finishing the £2.75 billion link has been all but straight, as it led to a wave of sanctions from the EU and US.
Ukraine has slammed the construction of the bridge by the ‘the occupation forces’, which has now been finished some four years after Russia annexed the peninsula.
The bridge will cope with 40,000 cars a day, travelling on four lanes between the mainland and Crimea, which is a popular Russian holiday destination.
Yesterday’s collapse isn’t the first accident to hit the newly built bridge. A storm tore a pontoon crane from its moorings and smashed it against the bridge last month.
The incident damaged a lighting pole, Russia’s Taman Federal Road Agency press service said.