SINGAPORE - The relationship between Singapore's Government and the country's workers is the strongest and longest-lasting in the world, Prime Minister Lee Hsien Loong said on Friday.

"Our unions are equal partners with employers and the Government," said PM Lee in his annual speech at the National Trades Union Congress (NTUC) May Day Rally.

This has allowed trade unionism to become a profession that unionists can be proud of, with union leaders sitting on key statutory boards and the National Wages Council.

While other governments may say they protect workers from competition and unscrupulous businesses, they often end up frightening off investors and damaging the economy, causing job losses for workers, said PM Lee.

On the other hand, other countries try to weaken union influence, resulting in tit-for-tat conflict, he added.

But in Singapore, the Government, workers and employers partner in growing and upgrading the economy, in a tripartite system that has delivered results "not just over one or two election terms, but over 50 years", he said, addressing some 4,000 unionists, employers and government officials at The Star Performing Arts Centre.

As a result, he is "aghast" when he hears opposition politicians claim that tripartism is obsolete and that workers must fight the Government and their employers.

Either these politicians do not understand the importance of tripartism, or they understand it but are not interested in workers' welfare and are trying to stir trouble to exploit workers for their own political ends, Mr Lee added.

"No trade union congress anywhere else in the world has been as effective as NTUC in improving workers' lives," Mr Lee said, adding that tripartism is a "precious legacy" that must be protected.

"This is why today, just as we had done every year for the past 55 May Day Rallies, we recommit ourselves to our promise - this Government will always be on your side, on the side of workers."