Russian Emergency Situations Ministry, Egyptian Military on cars approach a plane’s tail at the wreckage of a passenger jet bound for St. Petersburg in Russia that crashed in Hassana, Egypt.

The Kremlin said for the first time on Tuesday that a bomb had ripped apart a Russian passenger jet over Egypt last month and promised to hunt down those responsible and intensify its air strikes on Islamist militants in Syria in response.

Russia’s federal security service (FSB) on Tuesday said it would pay $50 million for information about “terrorists” who brought down the plane in Sinai last month with 224 people on board.

The FSB appealed for “help in identifying the terrorists” that exploded a bomb on the A321 plane travelling from Egypt to Russia. “There will be a reward of $50 million for information helping to arrest the criminals,” it said on its website.

Until Tuesday, Russia had played down assertions from Western countries that the crash was a terrorist incident, saying it was important to let the official investigation run its course.

But in a late night Kremlin meeting on Monday three days after extremist gunmen and bombers killed 129 people in Paris, Alexander Bortnikov, the head of Russia’s FSB security service, told a meeting chaired by President Vladimir Putin that traces of foreign-made explosive had been found on fragments of the downed plane and on passengers’ personal belongings.

“According to an analysis by our specialists, a homemade bomb containing up to 1 kilogram of TNT detonated during the flight, causing the plane to break up in mid air, which explains why parts of the fuselage were spread over such a large distance,” said Bortnikov.

“We can unequivocally say it was a terrorist act,” Bortnikov said in footage that was not released until Tuesday morning.

Putin responded by saying the incident was one of the bloodiest acts in modern Russian history and ordered the Russian air force to intensify its air strikes in Syria in response.

“It (our campaign) must be intensified in such a way that the criminals understand that retribution is inevitable,” said Putin.

Ordering the country’s secret service to hunt down those responsible for blowing up the plane, he said the effort to bring them to justice should be exhaustive.

“We will search for them everywhere wherever they are hiding. We will find them anywhere on the planet and punish them,” Putin said.

Egypt detains two airport staff

Meanwhile, Egyptian authorities have detained two employees of Sharm al-Sheikh airport in connection with the downing of the Russian airliner.

“Seventeen people are being held, two of them are suspected of helping whoever planted the bomb on the plane at Sharm al-Sheikh airport,” one of the officials said.

Egypt has not yet confirmed that a bomb was responsible, saying it wants to wait until all investigations are complete.

It was not immediately clear what role the employees had at the airport, which is Egypt’s third-busiest, handling a vast number of charter and budget flights for tourists seeking sea and sun in the southern Sinai peninsula.

Since the disaster, many flights to and from Sharm al-Sheikh have been suspended, raising concerns that Egypt’s tourism industry, worth about $7 billion a year and still a pillar of the economy despite having fallen sharply in recent years, will be further ravaged.

File photo shows an Egyptian military helicopter flying over debris from a Russian airliner which crashed at the Hassana area in Arish city.

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