"The Muslim community in Cardiff have been very concerned about these individuals,” Riverside councilor Mohamed Islam told The Wales Online on Thursday, February 2.
"We respect the courts and we believe that anyone who is involved in these sorts of activities should be punished severely.”
Four Islamist radicals admitted in court Wednesday that they plotted to attack the London Stock Exchange as part of a campaign of attacks across Britain.
The plot included plans to post bombs to the United States Embassy and the home of London Mayor Boris Johnson.
Police foiled the plot at an early stage before firm dates were agreed or explosive devices assembled.
The defendants were all British nationals with Bangladeshi or Pakistani backgrounds.
"They weren't coming to any community engagement or mosque," Islam told BBC Radio Wales.
Undercover officers had followed two of the conspirators in November 2010 as they made observations of London landmarks including the Big Ben clocktower, parliament, Westminster Abbey and the London Eye ferris wheel.
The two men, Mohammed Chowdhury, 21, and Shah Rahman, 28, both from east London, admitted preparing for acts of terrorism by planning to plant an improvised bomb in the toilets of the London Stock Exchange.
Brothers Gurukanth Desai, 30, and Abdul Miah, 25, both from Cardiff in Wales also pleaded guilty to the same charge.
The Muslim councilor said that the four were first noticed by the community in 2008.
"The only time they've been noticed was during the 2008 local elections when they came to the mosque and started distributing hatred leaflets and saying Muslims shouldn't vote, Muslims shouldn't be part of democracy.
