Appearing before the Justice V K Jain Tribunal, they said that four TRF members, arrested in 2009, had confessed that they were LTTE supporters and planned to launch attacks at important cities in India.
The four members were still being questioned, they said, adding that central government officials were also for extending the ban.
Two police inspectors from Chennai and a sub-inspector deposed before the tribunal, formed under the Unlawful Activities Prevention Act.