St Petersburg has been hit by a bomb blast on its metro, killing at least 11 people and injuring dozens more.

A Kyrgyz-born Russian has been named as a suspect behind the explosion in the city centre on Monday, though his motives are not yet clear. The attack on Russia's second city is the first major terror attack in the country since two suicide bombers killed 32 at a train station in Volgograd in 2013.

What happened?

A home-made bomb, believed to have been a shrapnel-filled briefcase, was exploded at 2.20pm local time on St Petersburg’s Metro, at Sennya Square, a busy intersection station where three of the city’s five subway lines meet. A second unexploded bomb was discovered shortly afterwards.

President Vladimir Putin, who was in the city at the time, said that all causes, including terrorism, were being investigated. A spokesman for the GKNB security service identified the suspect as Akbarzhon Jalilov, born in the city of Osh in 1995. He provided no other details, but authorities are exploring the possibility that it was a suicide bomb.

Kyrgyzstan, a predominantly Muslim Central Asian nation of six million, is Russia's close political ally and hosts a Russian military airbase.

The Foreign Office (FCO) website warns Britons in St Petersburg to take extra care and follow the advice of the local authorities. It adds that all metro stations in the city are currently closed.

The city’s airport, Pulkovo, said it is operating as normal.

Where is St Petersburg?

The city formerly known as Leningrad was described by its founder, Peter the Great, as Russia’s “window to Europe”, owing to its north-western position overlooking the Gulf of Finland.

Once Russia’s capital, St Petersburg has a population of 7.5million and is popular with tourists for its wealth of baroque and neoclassical buildings, rich history and the Hermitage, one of the world’s largest museums. It is considered the country’s most liberal, progressive city and has a bustling nightlife and cultural scene.

Around 150,000 Britons visit Russia each year, according to the FCO.

St Petersburg's Winter Palace, which houses the Hermitage Credit: Roman Evgenev/Roman Evgenev

Has Russia suffered terror attacks in the past?

St Petersburg was the destination of Metrojet Flight 9268 blown up over the Sinai peninsula in Egypt in October, 2015, after departing from Sharm el Sheikh. The attack, claimed by the so-called Islamic State, killed all 217 passengers and seven crew onboard.

The last major attack on Russian soil was in 2013 in Volgograd, when jihadist suicide bombers from Islamist and separatist group the Caucasus Emirate blew themselves up a day apart, first at the train station and next on a bus. It followed a similar attack two months earlier in the city.

In 2011 the same group bombed the arrival hall of Moscow’s international Domodedovo airport, killing 37 people and injuring scores more.

The Moscow Metro was hit in 2010 by the Caucasus Emirate who ordered two female suicide bombers to blow themselves up at two stations during a morning rush hour. Forty people died.

The capital’s subway system was attacked twice in 2004 by a group called Muslim Socity No 3, the first in February with 41 deaths near Avtozavodskaya station, the second months later in August outside Rizhskaya station, claiming 10 lives.

Perhaps the better-known attacks include the Belsan school siege in 2004, carried out by Chechen separatists, when more than 1,100 children and teachers were taken hostage in the region in North Ossetia. The eventual storming of the building ended the siege with the death of some 334 hostages.

The Moscow theatre siege ended with security forces storming the building Credit: 2003 AFP/AFP

The Moscow theatre crisis in 2002 was similar. Chechen rebels took 850 people hostage at the Dubrovka Theatre in a siege that lasted three days before special forces stormed the building. All the militants were killed and 133 hostages.

What does the Foreign Office say?

The FCO says nothing specifically about travel to St Petersburg and Moscow and advises that the majority of Russia, from the western fringes of Europe to the far eastern shores, is safe.

However, it advises against all travel to some south-western regions, including Chechnya, Ingushetia and Dagestan. It also advises against all travel to within 10km of the southern border with Ukraine, with whom Russia is engaged in a territorial dispute over Crimea.

The FCO advises against all travel to within 10km of the border with the Ukrainian Donetsk and Lugansk Oblasts.

against all but essential travel to within 10km of the border with the Ukrainian Kharkiv Oblast.

The FCO advises against all travel to Chechnya, Ingushetia and Dagestan and the districts of Budyonnovsky, Levokumsky, Neftekumsky, Stepnovsky and Kursky in Stavropol Krai.

against all but essential travel to North Ossetia, Karachai-Cherkessia and Kabardino-Balkaria (including the Elbrus area).

What does it say about terrorism?

“There is a high threat from terrorism,” it says. “The main terrorist threat in Russia comes from Islamist and rebel groups in the North Caucasus, but attacks aren’t limited to this region. Previous attacks have seen large numbers of casualties.

“Although there’s no indication that British nationals or interests have been specific targets, attacks could be indiscriminate, including in places visited by foreigners. You should be vigilant in all public places, including major transport hubs, tourist sites and crowded areas – particularly where access isn’t controlled (eg open-air events and markets). Previous attacks have targeted transport infrastructure. Further attacks are likely, and could take place anywhere in Russia.

The world mapped according to terror threat

“In the North Caucasus, while the number of casualties from ongoing violence has reduced in recent years, there continue to be frequent attacks and skirmishes between rebel groups and Russian forces in the republics of Dagestan, Chechnya, Ingushetia and Kabardino-Balkaria.”

It also warns of kidnapping in the North Caucasus region, with westerners “particularly vulnerable”.

Can I cancel my trip?

You can, but you will have to pay any extra costs you incur. Travel companies are not obliged to offer free cancellation or repatriation unless the FCO advises against travel - though some might make exceptions for specific incidents or destinations. It is worth checking with the company you booked with.

Will my travel insurance cover any losses if I don’t travel?

Not usually. Travel insurance normally excludes costs associated with such instability including terrorist action.