The A321 Airbus that crashed in October while carrying holidaymakers back to Russia from Egypt was destroyed by a homemade bomb, intelligence service officials in Moscow said on November 17, announcing a $50mn reward for information leading to the arrest of the perpetrators.

"We can say with confidence that this was a terrorist act," the Kremlin quoted Federal Security Service (FSB) chief Alexander Bortnikov as saying. According to Bortnikov, the airliner was blown up by a homemade explosive device equivalent to around one kilo of TNT. Traces of a foreign-made explosive were found in the airliner debris and the passengers' belongings, the official added.

Flight 9268 operated by Russia's Kogalymavia air carrier crashed on October 31 over the Sinai Peninsula 30 minutes after departing from the Egyptian resort of Sharm el-Sheikh. All 224 passengers and crew, mainly Russians, perished.

Russian President Vladimir Putin said that those guilty of the terrorist act on board the jetliner would be found and punished.

"This is not the first time that Russia experiences barbarous terrorist crime," Putin told a meeting with government and security officials late on November 16. "The murder of our people over Sinai is one of the bloodiest crimes in terms of the lives it claimed," Putin added, issuing a call for other countries to assist in tracking down and punishing those responsible for the destruction of the plane.

The president said Russia would be acting "in strict compliance with Article 51 of the United Nations Charter envisaging the right of countries to self-defense".

Following the November 13 terrorist attacks in Paris that killed at least 128 people, Putin repeated an earlier call made to the UN in September calling for a broad international coalition to fight against terrorism.

"This tragedy has become another testimony of terrorism's barbarity, which poses a challenge to human civilisation," Putin said in a telegram to French counterpart Francois Hollande, according to the Kremlin. "It is clear that the real unification of the international community's efforts is needed for an effective fight against this evil."

Extremist Islamist forces linked to the Islamic State (IS) claimed responsibility for both the Paris and Egypt attacks.

Putin reiterated the call for closer international cooperation against the terrorist threat during a meeting with US President Barack Obama at the G20 Summit in Antalya on November 15.