OTTAWA - A surge in counter-terrorism investigations is stretching RCMP resources to the limit, says Mike McDonnell, assistant RCMP commissioner for national security criminal investigations.

The Mounties have 848 active national security investigations underway - a 780 per-cent increase since 9/11, he said in an interview on Wednesday.

McDonnell added part of the increase is attributable to police improving their counter-terrorism skills.

"We know more now, we're getting better at identifying more, our investigators are getting better," he said.

The RCMP's improving relationship and information-sharing with the Canadian Security Intelligence Service is also responsible, he said.

"It's like a marriage where we're working our way through stuff, but we're going forward. So we're in (investigating potential terrorism) much earlier and collecting evidence and working towards disruption.

"What we're on to scares us, what we're not on to really scares us."