Russia’s northern capital of St Petersburg has closed its airspace, grounded all planes that haven’t taken off and is turning away inbound flights, according to reports on the morning of February 28.

By midday local time the skies were reopened, but not reason for the closure was given. 

"The skies over St. Petersburg are open, all temporary restrictions have been lifted," the city government said in a statement. 

The authorities have given no information as to the reason for the emergency measures. bne IntelliNews staff report that fighter jets have been scrambled and are flying over the city, according to telephone calls to residents in the city. The Telegram channel Baza also reports there are jet fighters in the air over the city.

The city's main airport Pulkovo was shut and air traffic control initiated the “carpet” plan that is a protocol used when there is an unknown object in the air that can jeopardise the safety of commercial flights.

Flighttracker online service also showed the skies over St Petersburg as empty of planes. The "carpet" plan is used when there is an illegal border crossing or unidentified aircraft in the controlled airspace.

A Vedomosti source in the Ministry of Defence confirmed the information about the introduction of the "carpet" plan.

Later, the government of St Petersburg reported that flights were delayed until midday local time, reports Vedomosti, while the airport itself was operating normally.

“At the Pulkovo airport, a flight delay of up to 12 hours has been announced. The airport and its services are operating normally,” the statement said.

Local media, Fontanka, citing sources, reported that an unidentified object was seen 160-200 km from St. Petersburg. According to the publication, these messages were transferred by the Ministry of Defence to Pulkovo Airport.

Russian President Vladimir Putin was immediately informed of the incidence, presidential spokesman Dmitry Peskov said.

"The president has all the information about this. <…> Let’s go by the statements and clarifications from the aviation authorities or the military that have already been given and that will follow," Peskov told reporters, when asked if the Kremlin was aware of the reason for closing the airspace over St. Petersburg.

Peskov declined to discuss whether the incidents in St Petersburg and Tuapse are related to the alleged incident at the airfield near Minsk. He referred the inquiries to the Russian Defence Ministry. "The Kremlin is unable to analyze all these incidents, all this information. This is done by special services and the Defence Ministry. Therefore, I recommend that you reach out to them," Peskov said.

Earlier, news media reported allegations that an airfield near Minsk had come under attack. The Kremlin declined to comment on the reports. As Peskov noted, "Belarus denied [these reports], and there’s nothing more to add." Earlier on February 28, news media and Telegram channels reported that a fire had broken out at an oil storage facility in the southern town of Tuapse, TASS reports.