Celtic manager Neil Lennon, a Catholic, has received sectarian threats and abuse for several years.
(CNN) -- Scottish police are investigating after parcel bombs were posted to the manager of one of the country's leading football clubs and two other high-profile figures.
Postal staff intercepted two suspicious packages addressed to Celtic's Northern Irish coach Neil Lennon last month.
Another was posted to the constituency office of politician Trish Godman, and then last Friday one was mailed to Paul McBride, Lennon's lawyer in a recent Scottish Football Association disciplinary case.
Both Godman and McBride are well-known supporters of the Glasgow-based club, the UK Press Association reported on Wednesday.
It is an intolerable state of affairs which must end ... it deserves condemnation from all right-minded people
--Celtic chief executive Peter Lawwell
--Celtic chief executive Peter Lawwell
"They were definitely capable of causing significant harm and injury to individuals if they had opened them," Detective Superintendent John Mitchell said of the bombs.
"It is important to say that there is no doubt that there is someone out there with information that can assist us and take this inquiry forward, and the quicker the better."
The 39-year-old Lennon was posted bullets in January, along with two other Celtic players, but they were intercepted in his native country before getting to Scotland.
He cut short his international career in 2002 after receiving a death threat from a protestant paramilitary group, having suggested he would like to play for an all-Ireland football team.
In 2008, Lennon was treated in hospital after being assaulted in Glasgow, with the incident again linked to sectarian rivalry.
He had needed the services of McBride after being charged with misconduct following a clash with the assistant manager of Celtic's arch-rivals Rangers last month.
McBride publicly accused the SFA of bias after Lennon was unable to overturn his suspension, while Ally McCoist successfully appealed against his ban and his Rangers players Madjid Bougherra and El-Hadji Diouf escaped punishment over other incidents.
The two teams -- Celtic's support is predominantly Catholic and Rangers' is Protestant -- will meet again on Sunday.
Celtic chief executive Peter Lawwell condemned the attempted bomb attacks.
"Neil Lennon is a football manager who simply wants to carry out this role to the best of his professional ability. However, in this horrific ongoing campaign, he and other Celtic personnel continue to be the subject of repeated threats and intimidation," he told the club's website.
"It is an intolerable state of affairs which must end. Celtic, from our inception, has been a club open to all. We enjoy friendship and respect throughout the world yet, here in Scotland, we are caught up in these vile events.
"The most recent targeting of Neil Lennon, Paul McBride and Trish Godman -- three people who are linked only by an affinity with Celtic -- deserves condemnation from all right-minded people."
