Russian President Vladimir Putin signed a decree on Saturday to strengthen measures for protecting transport crossing through the Kerch Strait, the power grid connecting Crimea and the main gas pipeline to the peninsula.

Putin authorized the Russian Federal Security Service to organize and coordinate measures to effectively protect these facilities, said the decree published by the Kremlin.

Russian divers on Sunday examined the damage left by the explosion. Russian Deputy Prime Minister Marat Khusnullin said the divers started work in the morning, with a more detailed survey above the waterline expected to be complete by day's end, domestic news agencies reported.

"The situation is manageable - it's unpleasant, but not fatal," Crimea's Russian Governor Sergei Aksyonov told reporters. "Of course, emotions have been triggered and there is a healthy desire to seek revenge."

Ukrainian President Volodymyr Zelenskyy did not mention the blast in his nightly video address on Saturday, highlighting only the weather in Crimea as being cloudy.

"Today was not a bad day and mostly sunny on our state's territory," he said. "Unfortunately, it was cloudy in Crimea. Although it was also warm."

Zelenskyy said Ukraine wants a future "without occupiers. Throughout our territory, in particular in Crimea."

In addition, Zelenskyy said in the video that the Ukrainian troops are involved in very tough fighting near the strategically important eastern town of Bakhmut, which Russia is trying to take.

"We are holding our positions in the Donbas, in particular in the Bakhmut direction, where it is very, very difficult now, very tough fighting," said Zelenskyy.

He also reiterated a call for Western countries to provide greater amounts of anti-aircraft systems.

Traffic has reopened to cars and buses with a full inspection procedure needed, while trucks are still required to cross the Kerch Strait by ferry, Crimea's head Sergei Aksyonov said.

Meanwhile, the railway service on the bridge has been fully restored and all scheduled trains, both for passengers and freight, will be able to cross the viaduct, Khusnullin said on late Saturday.

Thirteen trains have passed through the Crimean Bridge since the resumption of traffic, with about 6,000 passengers transported, Russia's RIA news agency reported Sunday.  

Why it matters

The 19km (12 mile) Crimean Bridge over the Kerch Strait is the only direct link between the transport network of Russia and the Crimean peninsula.

Putin personally opened the $3.7 million Kerch Bridge in May 2018 by driving a truck across it in a symbol of Moscow's claims on Crimea. The bridge, the longest one in Europe, is crucial for the supply of fuel, food and other products to Crimea, where the port of Sevastopol is the historic home base of Russia's Black Sea Fleet.

It consists of a separate roadway and railway, both supported by concrete stilts, which give way to a wider span held by steel arches at the point where ships pass between the Black Sea and the smaller Azov Sea.

It also became a major supply route for Russian forces after conflict between Ukraine and Russia started on February 24. Moscow used it to send forces from Crimea to seize most of southern Ukraine's Kherson region and some of the adjoining Zaporizhzhia province.

Zaporizhzhia missile attack

A Russian missile attack early on Sunday struck an apartment block and other residential buildings in Ukraine's southeastern city of Zaporizhzhia, killing at least 17 people and injuring 87 others, including 10 children, Ukrainian officials said.

Russian aircraft launched at least 12 missiles into Zaporizhzhia in the latest strike, partially destroying a nine-storey apartment block, leveling five other residential buildings and damaging many more, said Oleksandr Starukh, governor of the Zaporizhzhia region.

"We pulled people out quickly and saved eight people already, but when the fire starts then people (under the rubble) have practically no chance of surviving as there is no oxygen," he added.

Zelenskyy condemned the attack as "absolute evil" by people he called "savages and terrorists", vowing those responsible would be brought to justice.

Moscow denies attacking civilians during what it calls a "special military operation" to demilitarize its neighbour.

(With input from agencies)