Some of them yesterday said they had received calls from intelligence agencies inquiring about the protest. The teachers also worry that their telephones might have been tapped.

Dhaka University Teachers' Association (Duta) observed the two-day programmes on July 21 and 22 to protest the arrest of Awami League President Sheikh Hasina and the reported harassment of BNP Chairperson Khaleda Zia. The teachers wore black badges and did not take classes as part of the protest.

Duta President Prof Sadrul Amin said an intelligence official phoned him on July 22 to seek an appointment with him to inquire about Duta's protest programme.

"I agreed and told him to come at a certain time, but nobody turned up," he added.

At the night of July 21, police from special branches came to the Duta office and talked to Duta General Secretary Prof Anwar Hossain and Dean of Social Sciences Faculty Prof Harun-or-Rashid.

The issue was discussed at a meeting of the advisory council committee on law and order on Tuesday. The meeting asked the law enforcers to keep watch on developments on the DU campus.