A leading researcher warned the government on Thursday to prepare a new social security and welfare structure now to cope with the country's emerging 'grey population' whose size is growing steadily and will become the country's major age group in the next 20 years. 

Prof. Pramote Prasartkul of the Institute of Population and Social Research at Mahidol University said Thailand will have 13 million 'senior citizens' in 20 years, or 20 per cent of the population in terms of today's population of 65 million people. 

He advised persons born between 1963 to1983 to prepare now to be able to look after themselves when they reach retirement.

''At least 10 per cent of the current population--about 6 million--are senior citizens but not everyone is entitled to the government welfare and health insurance,'' Dr. Pramote said.

Thailand gives state welfare to civil servants and state enterprise employees but not to farmers or private sector employees.

The academic also urged private sector to help the government set up a pension scheme for retirees.

''The government must try to grow awareness on the issue among the public so that people will prepare and save up for their old age,'' according to Prof. Pramote.

He said Thailand's rapidly declining birth and death rates have been blamed for the foreseeable imbalance in the future population. He said Thai people have increasingly delayed their marriages and that most couples have less than two children. 

''We need to take Japan and some western European countries as examples," the Mahidol academic advised, "as they have got more senior citizens at an alarming rate.''

''But Japan has prepared a good system to cope with it," Prof. Pramote said. "In Japan even company workers have provident funds which help them save for their retirement, and the government also provide services to look after old people.'' 

However, he said Japan faces a shortage in the work force which would affects government revenues from income taxes, limiting the funds available to be spent on providing services and care for older citizens.

''It took those countries hundreds of years to face this problem but only 30-40 years for Thailand as our birth rate has dropped too rapidly--from 6-7 children per couple to less than two at the moment,'' he said.