MOSCOW — A homemade explosive device brought down a Russian passenger plane over Egypt last month, the head of Russia’s FSB security service said today, telling Russian President Vladimir Putin it’s now clear the bombing that killed 224 people was a “terrorist” act.

The Islamic State group has claimed responsibility for downing the Russian plane in written statements and on video and audio messages online.

FSB head Alexander Bortnikov said tests showed the explosives had been produced outside of Russia, but gave no further details.

Everyone on board, most of them Russian tourists, were killed when the Metrojet Airbus 321-200 crashed over the Sinai Peninsula on Oct. 31 about 23 minutes after taking off from Sharm el-Sheikh.