Suliman Mohamed, a 21-year-old from Ottawa, has been accused by RCMP of conspiring to participate in a terrorist activity with two twin brothers who were arrested on Friday.

Mohamed was arrested Monday and charged with one count of participation in the activity of a terrorist group and one count of conspiracy to participate in a terrorist activity.

Ashton Larmond, left, and his twin brother Carlos appeared in court on Saturday to face several terrorism-related charges. (Sketches by Laurie Foster-MacLeod) Police said Mohamed's arrest was linked to the arrests of twin brothers Ashton and Carlos Larmond on Friday . In a media release, RCMP allege Mohamed conspired to participate in terrorist activity with the Larmond brothers.

"I think it speaks to the issue of terrorism across Canada and the potential threat that exists here in our own country," said Ottawa police Chief Charles Bordeleau of the arrests on Monday, adding that the force continues to work closely with RCMP and Ontario Provincial Police on terrorism-related cases.

"I think our community is safer today as a result of these arrests, and we will continue to work with the RCMP — who have the overall mandate for terrorism — to support them in the work that they do that impacts here locally in our community," Bordeleau said.

Ashton Larmond, who was arrested at the Montreal airport before flying overseas, was charged with:

Facilitating terrorist activity.

Participation in the activity of a terrorist group.

Instructing to carry out activity for a terrorist group.

Carlos Larmond, who was arrested in Ottawa, was charged with:

Participation in the activity of a terrorist group.

Attempting to leave Canada to participate in terrorist activity abroad.

Both brothers were charged with drug possession in 2010 and were ordered to pay fines in 2011. Ashton Larmond was later charged for breaching conditions in relation to the drug possession offence and received a suspended sentence in 2011.

Mohamed, meanwhile, does not have a criminal record in Ottawa, according to court records.

"These recent arrests underscore the reality that there are individuals in Ontario and in Canada who have become radicalized to a violent ideology, and who are willing to act upon it," said Chief Supt. Jennifer Strachan, criminal operations officer for the RCMP in Ontario, in a media release.

The RCMP also thanked Ottawa police and Ontario Provincial Police for their contributions to the investigation, adding that the forces "play a valuable role in the early detection of threats in Canada and abroad."

Steven Blaney, the minister of public safety and emergency preparedness, was briefed by the RCMP about the latest arrest Monday, according to his press secretary, Jason Tamming.

"As you have heard from our security agencies, we continue to confront and address the significant challenges posed by high-risk travellers who may wish to go abroad to support or engage in terrorist activities," Tamming wrote in an emailed statement to CBC News.