Russia and Belarus will will deploy a joint military task force, Belarusian leader Alexander Lukashenko has announced.

Belarus started pulling forces together two days ago, Belarusian state TV cited Mr Lukashenko as saying in a security council meeting on Monday, accusing Ukraine of preparing attacks on the country.

The agreement with Russia follows "aggravation" on the country's western borders, the president said.

The country's ministry of defence should be ready to place troops "where necessary", he added.

Mr Lukashenko held a one-on-one with Russian President Vladimir Putin, a close ally, on the sidelines of a summit in St Petersburg on Friday, state TV reported.

Russian forces used Belarus as a staging post for their February invasion of Ukraine, sending troops and equipment into northern Ukraine from bases in Belarus.

The president also threatened Ukraine directly, making reference to a Saturday explosion which destroyed a key bridge linking Russia to the occupied Ukrainian region of Crimea, which Moscow annexed in 2014.

"Tell the president of Ukraine and other insane people, if they are still there, that the Crimean bridge will seem like flowers to them, if they even touch at least one metre of our territory," state outlet Belta TV cited Mr Lukashenko as saying.

Multiple cities in Ukraine were bombed on Monday, just hours after Putin blamed Kyiv for attack on the Kerch bridge.

Russia fired 75 missiles, including Iranian-made drones, at Ukraine the chief of the armed forces said.

Kyiv was struck by several blasts, breaking several months of relative calm in the city, with multiple people killed and wounded. Explosions were also reported in the western city of Lviv, as well as in Dnipro, Zhytomyr, Khmelnytsky and Ternopil.

At least eight people were killed and 24 were injured in just one of the Kyiv strikes, according to preliminary information, said Rostyslav Smirnov, an adviser to the Ukrainian ministry of internal affairs.