Prima facie, the number from which the messages have been sent is from outside the country, the Mumbai crime branch have launched investigations in the matter, an official said.
Mumbai Traffic Police's control room has received several messages on their WhatsApp helpline number, threatening a "26/11-type" terror attack, an official said on Saturday, according to the PTI.
A man was detained from Virar near Mumbai and the Mumbai crime branch team which is probing the threat messages is questioning him, sources told PTI.
Prima facie, the number from which the messages have been sent is from outside the country, he said.
"Threat messages were received on the WhatsApp number of the Mumbai police's traffic helpline operated from the control room in Worli around 11 pm on Friday," the official told the PTI.
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"In the series of messages, the sender has threatened about a 26/11-type attack," he said.
While one message says that six people will execute the attack, another mentions that preparations are on to blow up Mumbai, which will bring back the memories of the 26/11 attack, the official said.
The city police's crime branch has initiated an investigation into it, he added.
In one of the most horrific terrorist attacks in the country's history, 166 people were killed and over 300 injured as 10 heavily-armed terrorists from Pakistan created mayhem in Mumbai on November 26, 2008.
Meanwhile speaking to reporters at the airport in Nagpur city, Leader of Opposition in state Legislative Assembly, Ajit Pawar, on Saturday said that the threat messages received by Mumbai police should be taken seriously and central agencies should also look into it.
(With PTI inputs)