Former president of the Council of Trade Unions Helen Kelly has died in Wellington, aged 52.

The staunch unionist, advocate of workers' rights, and medical marijuana campaigner was diagnosed with terminal lung cancer last year.

Tributes are flowing for Helen, who was widely loved and respected by people from all parts of the community.

New Zealand Post Primary Teachers' Association communications advisor Liz Robinson is sorry to hear 'our union rock” has died.

'Helen never gave up fighting for working people from every sector – whether they be education staff battling for better working conditions, or saving the lives of forestry workers by advocating for improved health and safety protections,” says Liz.

'Helen dedicated her entire career to improving the working lives of others.”

Workplace Relations and Safety Minister Michael Woodhouse extends his condolences to her friends and family.

'Helen was a passionate advocate for the rights of New Zealand workers,” says Michael.

'I enjoyed our robust and respectful discussions on employment law and health and safety and admired her passionate advocacy of the causes she strongly believed in.”

NZ First leader Winston Peters says Helen Kelly had a heart for average Kiwis getting a fair chance.

'Regardless of anyone's political persuasion, New Zealanders admired her feisty commitment to workers and to the union movement.”

WorkSafe New Zealand Chief Executive Gordon MacDonald also paid tribute, praising Helen's part in putting health and safety 'front and centre” an issue the whole country needs to address.

'Helen Kelly was the first person, after the border control officers, I met when I arrived in New Zealand two and a half years ago,” says Gordon.

'I was jaded and tired after the trip from the UK but I left the airport totally re-energised after my first conversation with Helen.

'Helen was committed and passionate about health and safety. She was a constant presence, sometimes a critic and sometimes a supporter but without a doubt always intent on making life healthier and safer for people at work.

'I will miss her both professionally and personally. She will be missed but not forgotten by everyone associated with WorkSafe.”