Hyderabad, March 19 (IANS) The Hyderabad police have picked up five suspects in a case relating to a threatening letter to the chief justice of the Andhra Pradesh High Court, Nisar Ahmed Kakru.

Hyderabad Police Commissioner A.K. Khan told reporters Friday that police were questioning the suspects. 'A case has been registered,' he said.

The suspects reportedly include an advocate and two typists. The police are also looking for a man who dropped threatening a letter at the chief justice's residence in Banjara Hills neighbourhood last weekend.

In the typed letter on a stamp paper, an anonymous person warned the chief justice not to say anything negative about pro-Telangana advocates. He claimed that these advocates had the support of Maoists.

The letter was dropped a few days after the chief justice objected to the manner in which advocates boycotted the courts and staged protests March 8.

The advocates, supporting the cause of separate Telangana state, were protesting an attack on them by Telugu Desam Party (TDP) activists.

Police suspect that an advocate who participated in the protest could have written the threatening letter. They have stepped up security for the chief justice.