The bridge from the Russian mainland to the Crimean peninsula annexed by Moscow in 2014 was closed to car traffic due to military exercises, authorities said.
"The Crimean bridge is closed due to manoeuvres being carried out in the area," Moscow's governor in Crimea, Sergei Aksyonov, said via his Telegram channel on Wednesday.
Images of heavy clouds of smoke near the bridge fuelled speculation about another attack on the bridge. Late last year, it was severely damaged in a blast that dealt an embarrassing blow to the Kremlin.
Aksyonov said citizens should trust "only verified sources of information" because of the attack rumours.
The regional road construction authority has since reported the reopening of vehicle traffic.
At 19 kilometres, the bridge is the longest in Europe.
Russia had completed it in 2018, four years after the annexation of the peninsula. Since the beginning of the Russian war of aggression against Ukraine, it has also served to supply the Russian occupation forces in the south of the neighbouring country.
When a truck exploded in October 2022, both the road and railway bridges were damaged, so that traffic over this stretch was restricted for months. Russian President Vladimir Putin spoke of a terrorist attack by Ukraine and threatened retaliation. Russia then intensified its shelling of Ukrainian cities and infrastructure objects.
