As per Section 9 of Income Tax Act 1961, all income accruing or arising, whether directly or indirectly, through or from any business connection in India, or through any property in India, or through or from any asset or source of income in India, or through the transfer of a capital asset situate in India, shall be deemed to accrue or arise in India.
Therefore sale of property by an NRI in India is deemed to be accrue or arise in India. Thus it is taxable NRI also.