An explosion tore through Russia's bridge over the Kerch Strait, damaging it in a major blow to Vladimir Putin more than seven months into his invasion of Ukraine.

According to Russia's anti-terrorist committee, a truck exploded on the bridge's roadside in the early hours of Saturday morning, causing seven fuel tanks on the railway bridge to ignite.

Putin ordered senior officials and security agencies to investigate the explosion, which caused two road spans of the bridge to collapse and scorched part of the railroad.

It's another humiliation for Russia as it's invasion of Ukraine continues to struggle.

The bridge is a major conduit to supply Russia's war effort in south-eastern Ukraine where its troops have made substantial retreats in the last week from territory Putin claimed as Russian.

After a series of battlefield setbacks, Putin tried to raise the stakes by claiming the territories as Russian soil, justifying the deployment of the army's reserves, and threatening to use nuclear weapons.

The quagmire has only gotten worse. Many Russian people have left to avoid military service in order to avoid public criticism of the army.

The bridge was built after Russia annexed the peninsula from the Ukranian. In the second world war, the Wehrmacht and Red Army attempted to cross the waters linking the peninsula to the Russian mainland, but failed.

When Putin drove a truck across the bridge, he was accompanied by his childhood sparring partner Arkady Rotenberg, a billionaire who was in charge of the bridge's construction.

The Azov Sea to the Black Sea is a key route for shipping.

The bridge's collapse was hailed by Ukrainian officials.

A senior adviser to Ukrainian president Volodymyr Zelenskyy posted a picture of the bridge collapsing into the sea.

Everything that is illegal must be destroyed and everything that is stolen must be returned to Ukraine.

The first picture shows a bridge under the stars in the evening while the second shows it surrounded by clouds.

The national security chief of Zelenskyy posted a video of the bridge blowing up and a video of Marilyn Monroe singing Happy Birthday to JFK. Putin was 70 years old.

Numerous key infrastructure and military targets have been hit by explosions since the start of Moscow's full-scale invasion of Ukraine.

The attacks have not been formally claimed by Kyiv, but they have mocked Russia's attempts to assure the population by blaming the blasts on mundane causes.

A section of the bridge was engulfed in flames and smoke, which was visible on social media.

The dashboard camera footage shows that some passenger vehicles were on the road when the explosion happened. The footage was not verified by the Financial Times.

Structural damage to the bridge could be seen in other footage. Parts of the motorway were shown submerged in the strait.

The bridge was closed after the fire was put out.

It was not yet known how long it would take to rebuild the bridge.

Roman Olearchyk reported additional information in Kyiv.