Kolkata, Jan 6 : The Enforcement Directorate has requested the Border Security Force (BSF) to heighten its surveillance as the probe agency believes that heavyweight Trinamool Congress leader Sajahan Sheikh, who has been absconding since the attack on ED and CAPF personnel during a raid at his residence in West Bengal's North 24 Parganas district, might make an attempt to flee to Bangladesh. ED officials have requested the BSF to aggravate its surveillance at the different international borders with Bangladesh in the North 24 Parganas district, informed source said. The attack on the ED and CAPF personnel took place on Friday morning and since then Sajahan but his family members are on the run. The sources said that since the area where the attack took place is close to the international borders with Bangladesh, the EDis not ruling out the possibilities of an escape attempt to the neighbouring nation. They added that from the nature of the attack two things in the entire conspiracy are clear -- the first is that Sajahan received advance information of the raid and search operations and got time to arrange the huge crowd to assemble near his residence. The crowd waited, till the time the ED officials attempted contacting those within the residence locked inside. The ED has confirmed that while they were knocking the main entrance door of the residence, Sajahan was inside the house as indicated by the latter's mobile tower location. The second evident part of the conspiracy was the presence of women protesters in the front of the crowd, while male agitators hurled stones from behind. Because of the presence of the women in the front, the CAPF personnel had to refrain from a forceful counter-retaliation. It was only when the ED officials tried to retreat and separated from the escorting CAPF personnel, the male protesters came ahead of the women and attacked the central agency team with bamboo sticks, bricks and stones. /IANS