Russia on Friday praised the work of its air defences, saying they had downed 42 drones over the Moscow-controlled Crimean peninsula, a day after Ukraine claimed its forces launched a raid there.

Turkey's foreign minister meanwhile, in Kyiv for talks with Ukrainian President Volodymyr Zelensky, insisted that the best option to resume the country's grain exports was to find a way back to the original agreement with Russia that Moscow abandoned.

Crimea, annexed by Russia in 2014, has been targeted by Kyiv throughout Moscow's Ukraine offensive but has come under more intense attacks in recent weeks.

"All air defence systems are working quite effectively," Kremlin spokesman Dmitry Peskov said, adding that "minor damage" was sometimes unavoidable. He was responding to a question about the increasingly frequent drone attacks, after waves of drones were downed over the peninsula.

Moscow has been targeted by almost daily drone attacks in recent days.

And the Kaluga region was also targeted by a "missile" overnight, which was detected and destroyed by air defences, the ministry said.

Flights to and from Moscow's Vnukovo and Domodedovo airports were briefly halted, the TASS news agency reported, without specifying the reason.

- 'Engaged in combat' -

A local Russian-installed official earlier said several drones had been destroyed in the sea near Sevastopol, which is home to Russia's Black Sea fleet.

Emergency services reported no damage to civilian infrastructure from those drones, the Moscow-backed governor of Sevastopol Mikhail Razvozhayev wrote on Telegram.

"All forces and services are in a state of combat readiness," Razvozhayev said.

Russian military bloggers have criticised air defence around the peninsula, especially after Ukraine destroyed a powerful anti-aircraft system there on Wednesday. 

And on Thursday, Ukraine said its forces had landed on the peninsula and flown the country's flag during a "special operation" to mark its Independence Day.

Special forces troops landed overnight on Crimea's western shore near the towns of Olenivka and Mayak, where they "engaged in combat", Ukraine's GUR intelligence agency said.

Moscow has also accused Ukraine of attacking the Russian-built Crimean bridge, which connects the peninsula to Russia.

The bridge has been closed due to multiple incidents including a massive explosion in October last year.

Reports of the aerial attack came as the Pentagon said it would begin training Ukrainian F-16 pilots in the United States starting next month.

The jets have long been sought by Kyiv, now bogged down in a plodding counter-offensive aimed at retaking land held by Russian forces.

US President Joe Biden and Zelensky spoke on Thursday about plans to train Ukrainian pilots to fly F-16 fighter jets, the White House said.

- Grain talks -

Turkey' Foreign Minister Hakan Fidan made a rare visit to Kyiv Friday for talks with Zelensky on how best to solve Ukraine's grain export problem.

Russia last month pulled out of the landmark agreement that enabled Ukraine to export more than 30 million tonnes of grain from three Black Sea ports. It later warned that it could attack any ships travelling to or from Ukraine's Black Sea ports.

Ukraine this month sent a cargo vessel to Istanbul to test an alternate route reportedly backed by the United States, staying in waters controlled by NATO members Romania and Bulgaria before reaching Turkey.

But Fidan told reporters in Kyiv that Turkey felt the best option remained a return to the deal it had helped broker with Moscow.

"We know alternative routes are being sought (for grain shipments) but we see no alternative to the original initiative because they carry risks," he said.

"Revitalising this initiative is a priority for Turkey," he said. Fidan also visited a memorial for fallen soldiers in Kyiv.

Zelensky hailed what he said was an "important" meeting with Fidan.

"We also talked about the situation that has arisen due to Russia's dastardly attacks on grain exports in the Black Sea region," he said on Telegram.

In recent weeks Moscow has struck Ukrainian infrastructure in the Black Sea port of Odesa and ports along the Danube river.

Kyiv has attacked several Russian vessels in the Black Sea, including an oil tanker. It has also threatened ships travelling towards ports occupied by Russian forces.

Ukraine's EU neighbours Hungary, Poland, Romania and Slovakia -- as well as Bulgaria, which does not border the country -- decided to extend their ban on Ukrainian grain imports until the end of the year, the Polish agriculture minister said Friday.

The restrictions are set to expire on September 15.

bur/jj/lcm