Patrolling policemen detected the explosives, lying abandoned in the platform, and wrapped in an old newspaper at 11.45 am -- minutes after the Jammu-Tawi Express left the station.

They said the materials, confirmed by explosive experts as RDX, were contained in 25 polythene packets of different weights. Security in the station has since been tightened and the State police, GRP and RPF jawans had cordoned off platforms no five to nine for search operations.

At about 1 pm, the police released platforms no five and six for normal train operation and other platforms after 45 minutes.

During a joint operation carried out by CID and district police, five kgs of explosives, suspected to be RDX, were recovered from a person crossing over from Bangladeshalong Fulbari border in West Bengal's Jalpaiguri district yesterday, a Siliguri report, quoting police sources, said. The person however managed to escape.

Three pieces of energiser, one blaster and three time devices were also recovered, said Inspector General of Police, North Bengal, K K Das said today.

The explosives and the devices were suspected to be used in a blast in North Bengal on Independence day, Das said. The operations were carried out after interrogation of suspects of the New Jalpaiguri (NJP) station blast in June, he said.

Security in North Bengal, beefed up after the blast, has been further tightened and experts have been called from Calcutta to examine the explosives, Das added.