Three suspected suicide bombers may be looking for new targets in the country's financial capital Mumbai with police on Friday releasing their sketches after they apparently carried out reconnaissance of sensitive spots like Mahim dargah, Haji Ali shrine and Mahalaxmi temple last week.

The three men along with a burqa-clad (veiled) woman used a taxi to scan the city under suspicious circumstances on October 22 and 23 as part of a possible terror plot, police said.

J J Hospital and Hilton towers were the other two spots where the four had visited as the police launched a massive manhunt to trace them.

"The sketches were made as per the description given by the taxi driver," Joint Commissioner of Police (Law and Order) K L Prasad said.

He said police have been searching for the trio for the last two days and added that they could be fidayeen (suicide bomber).

Police said the three men and the woman halted at each of the five spots for a couple of hours and talked in hushed tones while inside the cab.

Police did not give any clues about the men or their possible whereabouts but the sketches suggested they were middle-aged. One had a beard while another had a moustache and the third was clean shaven.

With the festival season at its peak, Mumbai was on high security alert and the sketches were distributed far and wide.

The suspects allegedly asked the taxi driver to keep two bags containing 'unknown material' with him while leaving the cab near the Siddhivinayak Temple on October 23, following which the driver got suspicious and had a heated argument with them. The driver later contacted the police.

Prasad appealed to people to come forward with any information about the three as they could potentially be linked to some terror groups.

Prasad was also critical of the Anti-Terror Squad officers who had leaked the information to a section of media on Thursday and said the leak would affect police probe.

"We are appealing to people now because everything is out in the open. It is a very serious concern if a police official leaks operational information for petty reward," he said.

Prasad said adequate security has been provided to the taxi driver.

Police did not give any details about the burqa-clad woman. Regarding the security arrangements at different spots where the trio were suspected to have carried out recce operation, Prasad said, "Security at these spots are in place since the beginning of the festival season starting from Ganeshotsav in September."

People can give information about the trio by dialing 100 and 103 on the telephone, he added.

The information about the terror suspects came weeks after the country's two key stock exchanges in Mumbai received e-mailed bomb threats. The sender of the e-mails has not been identified.