Four persons, including two women, were on Monday arrested under the Prevention of Terrorism Act in connection with the twin blasts that rocked the metropolis on August 25.

Three of them were produced in the Special Court of A P Bhangale and remanded to police custody till September 15.

The other accused Sayyed Mohammed Abdul Rahim (45) could not be produced in the court since he was admitted to a hospital.

The three remanded to police custody were Arshad Shafique Ansari, Fahimida Sayyed (37), wife of Sayyed Rahim, and their daughter Fareen Sayeed (17)

This is for the first time that women have been arrested under POTA.

All the accused are allegedly involved in explosions at Ghatkopar that occurred on July 28 as well as the twin blasts at Zaveri Bazar and Gateway of India in south Mumbai on August 25, Prosecutor Rohini Salian informed the court.

All the accused hailed from Mumbai.

The prime suspect Naseer is yet to be traced.

The police seized 205 gelatine sticks, 20 detonators, 12 alarm clocks with timer, electric wires, soldering machine, clipper machine, polyester yarn and white metal clipper machine and crackers from the possession of the accused, the court was told.

On a query by the court, the accused said they did not have any complaint against the police.

The four were among five people detained on Sunday on the basis of description given by taxi driver Shivnarayan Pandey, whose vehicle was hired by the terrorists and in which a bomb exploded at the Gateway of India.

On the basis of graphic description given by Pandey, the police had drawn up sketches of suspects and circulated the same in all city police stations and elsewhere in Maharashtra.

The police teams had also been despatched to various places to trace the suspects.

Pandey had disclosed that a family of two men and a woman had hired his taxi in suburban Andheri on the ill-fated day for sight seeing and had asked him to proceed to Gateway of India where they broke journey for lunch.

He returned after 30 minutes to find that his taxi was blown off in the blast. He then volunteered to inform police about the suspects.

The police said for the first time after 1993 blasts, RDX was used in the twin explosions. They are finding out the source of RDX. The police are probing whether it came from outside the country or was the 'residue' of the 1993 explosives.

However, police sources said the possibility of RDX coming from outside the country was stronger.

The August 25 incident is the sixth bomb blast in the metropolis within a span of nine months since December 2, 2002.

More than 20 people have been arrested under stringent POTA for their alleged role in blasts and most of them were affiliated to outlawed Students Islamic Movement of India.

Among the accused are Saquib Nachan, former activist of SIMI, who hailed from Padgha village in nearby Thane district.

The police also seized a huge cache of arms from a well in Padgha village in the aftermath of the blasts.

One of the accused was a professor of Urdu at the premier National Defence Academy in Pune. He is facing the charge of harbouring terrorists, who had allegedly planned explosions to destablise the country's commercial capital.

Most of the accused are highly educated and some of them are doctors, MBAs and engineers, the sources said.

Among them is Dr Abdul Mateen, who was lecturer of Forensic Science in a medical college attached to J J Hospital.

Another accused Khwaja Yunus had escaped from police custody after the police van met with an accident in Ahmednagar district.

The Special Court had ordered an enquiry to trace his whereabouts but so far nothing has been discovered.

Complete coverage of the Mumbai blasts