OTTAWA -- The remains of two young men from London, Ont., were indeed among those found at the site of a deadly terrorist siege in Algeria in January, the RCMP confirmed Thursday.

Police in Ottawa summoned reporters to a unusual news conference to formally identify the pair as Ali Medlej and Xristos Katsiroubas -- and to plead for the public's help in their ongoing investigation.

"We are continuing our work and gathering evidence in this case to determine the circumstances that led to Ali Medlej and Xristos Katsiroubas departing Canada," said RCMP Supt. Marc Richer.

"The reality is, we need the public's help. This is a community issue; everybody has a role to play in this, and people may be in possession of a piece of information that they might find benign ... pick up the phone and call the number on the screen. That's what we want people to do."

Medlej and Katsiroubas are believed to have played key roles in the January attack on a natural gas plant, which killed at least 38 hostages and 27 other militants.

No other details about the pair or about other potential suspects are being released for fear it could end up compromising the investigation, said Richer.

Aaron Yoon, a high school friend also from London, travelled overseas with Medlej and Katsiroubas. Reports Thursday said Yoon is currently behind bars in Mauritania.

Richer would not say how long the RCMP investigation has been ongoing, or whether it predates the January attack, but did allow it has been underway for a "number of months."

The Canadian Security Intelligence Service reportedly began asking questions about Medlej and Katsiroubas after a family member contacted authorities in 2007 with concerns about the pair. It's unclear what became of that investigation.

Richer said all Canadians have a responsibility to ensure that "radicalization" is quickly nipped in the bud.

"Ultimately, countering radicalization to violence also depends on the public taking an active role in intervention, including assisting law enforcement by reporting suspicious and illegal activities," he said.

Small, even mundane pieces of information can help the investigation, he added.

"Who individuals might hang out with, who may or not have a good or bad influence on someone that may lead to certain behaviour, or observing these people and how they behaved and clues that people may have had either in discussions or in just in social settings with these people that may have triggered: 'Oh that's odd,"' he said.

"It may be many things, but if people around these two individuals noticed something that didn't fit over the course of time before these events that they believe might be useful, that's what we're looking for."

Richer said anyone with information is urged to call the RCMP's national security information network at 1-800-429-5805.