The leader of Flintshire Council said he was “left both saddened and numb” by the death of his friend of more than 20 years and added “the Labour family across Flintshire is absolutely devastated”.

Cllr Aaron Shotton said Mr Sargeant was “a passionate and tireless campaigner for Alyn and Deeside, the area in which he grew up, loved and proudly represented since 2003”.

He added: “I have known Carl as a colleague and friend for over 20 years serving alongside him on Connah’s Quay Town Council and was proud to act as his election agent at the 2011 Assembly election.

“His unique sense of humour and dedication to serving his community will be sadly missed by so many local people.

“The thoughts and prayers of the Labour group at the council are with Carl’s family, Bernadette, Jack and Lucy at this traumatic time.”

Cllr Bernie Attridge, deputy leader of Flintshire Council and chairman of FC Nomads of Connah’s Quay, of which Mr Sargeant was president, said: “I am so sorry. Carl has done lots for this constituency. He was a very big supporter of the Labour Club in dark days.

“Ten to 12 years ago it looked like we were going to go under and he helped me as a chairman to secure a future and I will always be grateful to him.

“I offer my condolences to the family, but at the present time I can’t speak to them, it’s so shocking.”

In a joint statement Cllr Brian Lloyd and Cllr Paul Cunningham, chairman and vice-chairman of Flintshire Council respectively, said: “We are deeply saddened to learn of the tragic death of Carl Sargeant.

“On behalf of the elected members and officers of Flintshire Council we extend our condolences to Carl’s close family and friends. We cannot begin to understand how deep their sense of loss and trauma must be.

“We invite the communities of Alyn and Deeside and the county of Flintshire to join us in offering support and comfort to Carl’s family at this very difficult time.”

FC Nomads of Connah’s Quay, of the Welsh National League Premier Division, said they would cancel all the club’s fixtures for this coming weekend as a mark of respect.

Mr Sargeant was a former chairman of Connah’s Quay Town Council.

Cllr Chris Risley, who is chairman now, said: “Carl was a valued and well respected member of the local community and was a firm believer in social justice.

“His tireless work in the Welsh Assembly and local area bringing in policies to help all communities will form part of his legacy – as will his dedication and the support he gave to the residents of Connah’s Quay and right across Alyn and Deeside.

“Carl will be sorely missed by everyone and it will take some time to come to terms with this heart-breaking loss.”

As a mark of respect, candidates in the Buckley Bistre West county council by-election have postponed campaigning until polling day tomorrow.