Indians who neglect their aging parents face possible prison under a new law passed by worried politicians.

The law, passed late on Thursday, reflects concerns that rapid modernization and a growth in nuclear families is undermining a centuries-old social fabric of extended families.

"At least now the elderly can have a roof to live under and food to eat in their old age," Gyan Prakash Pilania, a Hindu nationalist MP, was quoted as saying in local news reports.

Under the law, Indians can face up to a month in jail if found guilty of parental neglect.

The law also allows authorities to order children or relatives to pay a monthly maintenance allowance to the aged.

(Reporting by Alistair Scrutton; Editing by Y.P. Rajesh and Alex Richardson)