In the case of any person referred to in clause (vi) of Explanation 3 to sub-section (2) of section 2, if the competent authority, on the basis of the information and materials available to it, has reason to believe (the reasons for such belief to be recorded in writing) that any property held in trust is illegally acquired property, it may serve a notice upon the author of the trust or, as the case may be, the contributor of the assets out of or by means of which such property was acquired by the trust and the trustees, calling upon them within such time as may be specified in the notice which shall not ordinarily be less than thirty days, to explain the source of the money or other assets out of or by means of which such property was acquired or, as the case may be, the source of the money or other assets which were contributed to the trust for acquiring such property and thereupon such notice shall be deemed to be a notice served under section 6 and all the other provisions of this Act shall apply accordingly.
     Explanation.--For the purposes of this section "illegally acquired property", in relation to any property held in trust, includes--
         (i) any property which if it had continued to be held by the author of the trust or the contributor of such property to the trust would have been illegally acquired property in relation to such author or contributor;
         (ii) any property acquired by the trust out of any contributions made by any person which would have been illegally acquired property in relation to such person had such person acquired such property out of such contributions.