Russian President Vladimir Putin, driving a truck, unveiled the auto section of a new road and rail bridge linking Russia to the annexed Crimean peninsula on Tuesday, defying Ukraine.

Ukraine said the move showed cynical disregard for international law.

Putin drove the Russian-made KAMAZ dump truck in a convoy of vehicles across the 19-kilometre bridge over the Kerch Strait. Some Russians are calling it "Putin's bridge," designed to link Crimea into Russia's transport network.

CBC's Chris Brown reports from Moscow on the multi-billion-dollar project 1:47

At a ceremony broadcast live on state TV, Putin, dressed in blue jeans, was met by cheering workers on the Crimean side.

"At last, thanks to your talent, this project, this miracle, has happened," Putin told the workers.

In Kiev, Ukrainian President Petro Poroshenko slammed Putin's actions.

"The illegal construction of the Kerch bridge is the latest evidence of the Kremlin's disregard for international law," Poroshenko said.

"It is particularly cynical that its opening is happening on the eve of the latest anniversary of the deportation of the Crimean-Tatar people by the Stalin regime."

A photo taken in April of the bridge over the Kerch Strait designed to connect the Russian mainland with Crimea, which Russia annexed from Ukraine in 2014. (Pavel Rebrov/Reuters)

Russia annexed Crimea from Ukraine in 2014, drawing sanctions and prompting a deterioration in ties with the West.

The bridge's opening ceremony drew further criticism.

"France condemns the construction by Russia of the Kerch Bridge, which deprives Ukraine of full access and the use of its internationally recognized territorial waters," a French foreign ministry spokesperson said.

The spokesperson for the European External Action Service said in a statement on Tuesday that the bridge was "another violation of Ukraine's sovereignty and territorial integrity."

"The European Union continues to condemn the illegal annexation of Crimea and Sevastopol by Russia and will not recognize this violation of international law," the spokesperson said.

Many in Russia saw the bridge as a move toward restoring Moscow's rule over a historically Russian region. Built at a cost of 223 billion roubles ($3.6 billion US), it will be the longest dual-purpose span bridge in Europe.

The Kremlin said it would be opened to cars on Wednesday and the rail section was due to be completed at the end of 2019.

"Putin initiated this project himself. Many didn't believe these plans were possible," Kremlin spokesperson Dmitry Peskov told reporters on Tuesday ahead of the ceremony.

"This is an extremely important day from this point of view and in a practical sense and in symbolic terms."

The road stretch of the bridge was due to be completed by the end of 2018, but the opening was moved up at Putin's request. He inspected the bridge in March ahead of the presidential election he won, saying it was important to have the link to the Black Sea peninsula open for the summer tourist season.