Sisters in Islam (SIS) wants Putrajaya to address the issue of polygamous men secretly marrying their wives in Thailand.

Such cases involved men who do not qualify to take more than one wife in Malaysia, but do so anyway by having the solemnising ceremony in southern Thailand.

SIS said its study on polygamy found 32 percent of respondents who married in Thailand do not register their marriages in Malaysia, therefore the marriages are not recognised by Malaysian law.

"Secret marriages in Thailand negatively impacts not only wives but also children from the marriage, as their rights are not protected by Malaysian Islamic family law," it said in a statement today.

SIS said the Malaysian government should work with Islamic religious councils in Southern Thailand to conduct background checks.

As such, the NGO welcomed efforts by Minister in the Prime Minister's Department Jamil Khir Baharom to meet with Southern Thailand Islamic leaders.

SIS reiterated the criteria for polygamy in Malaysia under Islamic Family Law (Federal Territory) Act 1984.

They include that the husband must be financially capable of practising polygamy, can be fair to his wives, and the new marriage will not be detrimental to his existing wives.

It stressed that secret polygamous marriages in Thailand went against the objectives of marriage in Islam.