Mumbai police has received text messages warning of a "26/11-like" attack on the city from a phone number with Pakistan's country code and a person has been detained in this connection, officials said on Saturday. A man was detained from Virar near Mumbai and the Mumbai crime branch team which is probing the threat messages is questioning him, sources said.

The messages were received on WhatsApp on a helpline number of traffic police's Worli control room around 11:45 on Friday night. While one message said that six people will execute the attack, another said preparations were on to blow up Mumbai which will bring back the memories of the 26/11 attack, officials said.

"Police received messages around 11.45 pm on Friday, which threatened that a 26/11-like attack would be carried out in Mumbai and the city would be blown up. There was a mention of 26/11 attacks terrorist Ajmal Kasab and (deceased) Al Qaeda leader Ayman al-Zawahiri in the messages," city police commissioner Vivek Phansalkar said at a press conference on Saturday. "It was also mentioned that some of their aides were working in India. Prima facie, the threat messages came from a number that has the country code of Pakistan," he added.

Police have taken the messages seriously, he said, assuring that citizens' safety and security was police's responsibility.

"Necessary measures are being taken to investigate the threat messages. We are alert on coastal security and are coordinating with the Coast Guard," he added.

'Sagar Kavach' operation has been launched and coastal security beefed up, the police commissioner added.

The ten Pakistani terrorists including Kasab who caused mayhem in Mumbai and killed at least 166 persons had arrived in the city by sea route on November 26, 2008. Phansalkar, meanwhile, said a First Information Report (FIR) was being registered under Indian Penal Code section 506 (2) (criminal intimidation) at Worli Police Station regarding the threat messages.

The crime branch is also sharing the information with the Maharashtra Anti-Terrorism Squad, he added.

Police were also investigating the numbers and persons mentioned in the messages, he said, adding that these numbers were Indian ones.

Asked about the fact that the messages were in Hindi and not in Urdu and whether there was an attempt to create a fake IP address so that the messages would appear to have come from a Pakistani number, he said, "We can not rule out any possibility without investigation." Asked about media reports tracing the number to a Lahore-based gardener who claimed that his number had been `hacked', the commissioner said police were looking into this aspect too.

Police are already on high alert during the ongoing festive season, he said.

The threat messages were received a day after a yacht was found off the Raigad coast near Mumbai with AK-47 rifles and live rounds on board, causing a scare, although officials said that there was no terror angle in it. Speaking to reporters at Nagpur airport, Leader of Opposition in the Maharashtra Assembly Ajit Pawar said the threat messages should be taken seriously and central agencies should also look into them.