NEW DELHI, Feb 2: The Supreme Court today imposed a ten-year sentence of rigorous imprisonment on four associates of underworld don Dawood Ibrahim in a TADA case.The four accused - Shyam K Garikapatti, Subhash Singh Thakur, Jayendra (Bhai) Thakur and Chandranta Anna Patil - had been sentenced by a Delhi TADA court to five years imprisonment which was today enhanced to ten years. The four accused along with former Union minister Kalpnath Rai had appealed to the Supreme Court against the sentence imposed on them by TADA court Judge S N Dhingra in connection with the TADA case.But last November, the apex court allowed appeals of Rai and some others and acquitted them of the charge.