MOSCOW (Reuters) -Russia's Federal Security Service said on Wednesday that it had detained five Russians and three citizens of Ukraine and Armenia in connection with the bombing of a vital bridge to Crimea, an attack it said was masterminded by Ukraine.
The FSB said the attack was organised by Ukrainian military intelligence and its director, Kyrylo Budanov - echoing accusations by President Vladimir Putin over what he has called a "terrorist attack" against critical civilian infrastructure.
"The organizer of the terrorist attack on the Crimean Bridge was the Main Intelligence Directorate of the Ministry of Defense of Ukraine, its head Kyrylo Budanov, its employees and agents," said the FSB, the main successor to the Soviet-era KGB.
Ukraine has not officially confirmed its involvement in the bridge blast on Saturday, but some Ukrainian officials have celebrated the damage and an unidentified Ukrainian official told the New York Times that Kyiv was behind the attack.
The FSB said the explosive device was camouflaged in rolls of construction polyethylene film on 22 pallets with a total weight of 22.7 tonnes, and moved from Ukraine to Russia via Bulgaria, Georgia and Armenia.
"Control over the movement of the cargo along the entire route and contacts with participants in the criminal transportation scheme were carried out by an employee of HUR MO," the FSB said in a statement, using the acronym for Ukrainian military intelligence.
The 12-mile (19 km) road and rail bridge, a prestige project personally opened by Putin in 2018, had become logistically vital to his military campaign, with supplies to Russian troops fighting in south Ukraine channelled through it.
The explosion wrecked one section of the road bridge, temporarily halting traffic. It also destroyed several fuel tankers on a train heading towards the annexed Crimean peninsula from neighbouring southern Russia.
On Monday Russian forces launched mass missile strikes against Ukrainian cities, including power supplies, in what Putin said was retaliation for the bridge bombing.
The FSB, headed by Putin ally Alexander Bortnikov, also said that it had prevented Ukrainian attacks in both Moscow and the western Russian city of Bryansk.