Families of victims of a downed plane flying from Congo to Paris 20 years ago commemorated their loved ones at a ceremony in a Paris cemetery Saturday and renewed their calls for an end to terrorism.

At a somber ceremony at the landmark Pere Lachaise cemetery, the names of each of the 170 victims of UTA Flight 772 were read out.

UTA Flight 772 crashed over the Sahara Desert Sept. 19, 1989, after an explosion on board caused the aircraft to break up midair. All of 156 passengers and 14 crew members on board were killed.

An investigation into the attack concluded that a bomb had been smuggled into the plane’s luggage hold. Six Libyan agents were blamed for the attack.

In 1999, a Paris court tried and convicted the six men in absentia since Libyan leader Muammar Gaddafi would not allow their extradition to France.

The attack is widely believed to have been an act of revenge against France for supporting Chad in its conflict with Libya.

Saturday’s ceremony came on the second day of an anti-terrorism conference in Paris that saw families of victims of terrorist attacks in Europe call on their governments to do more to fight international terrorism.

“Terrorism is a terrible thing, it should be constantly condemned,” said event organiser Guillaume Denoix de Saint Marc, who lost his father in the UTA bombing. “The best way to advance is never to forget. It's not about living in the past, but what's happened should never be forgotten."

For Noel Chevrier, a former UTA pilot, the occasion was a chance to renew the pledge to fight terrorism. "The feeling is we need to distance ourselves from the sad memories and tears,” he said. “Now we need to take this energy and use it to make a more positive future."