The Lotus brand of analogue clocks has spelt terror among the security personnel across the country.

The top officials of the state and the central intelligence agencies were taken aback after they came to know about the use of Lotus brand of analogue clocks as timer devices in the bombs recovered from a flat at the Bahadurpur Housing Colony area in Patna on Monday night.

The same brand of clocks was earlier used in terror attacks in Patna, Bodhgaya (Bihar), Delhi, Ahmedabad and Jaipur.

While one of the three bombs exploded inside the flat, the personnel of the bomb disposal squad defused two explosives the same night.

A source in the National Investigation Agency (NIA) said the analogue clocks manufactured in Gujarat's Rajkot district were purchased by an alleged Indian Mujahideen operative, Tehsin Akhtar, from Guwahati, the capital of Assam, before the serial blasts during Hunkar Rally in Patna's Gandhi Maidan on October 27, 2013.

The source said Akhtar, a resident of Samastipur in north Bihar, had purchased 170 analogue clocks of Lotus brand before the Gandhi Maidan serial explosions, which left six persons dead and over 80 others injured.

"Of them, as many as 23 clocks were used in Bihar for carrying out two attacks (Bodhgaya and Patna). A few bombs were recovered during a raid in Mangalore," Akhtar had allegedly told his interrogators.

A senior police officer, who is a member of the team investigating into the Bahadurpur colony blast case, said the worry is that 110 clocks were still in the possession of the suspected IM operatives.

"It was Akhtar, who had brought the consignment of Lotus brand of watches to Bihar prior to Bodhgaya blasts on July 7, 2013," the officer said on the condition of anonymity.

Akhtar later handed over the clocks to his lieutenant Haider Ali, the alleged mastermind behind the Bodhgaya blast.

"We are trying to find out the reason behind the terror outfits' preference for the special brand of clocks being used as timer devices in bombs," the officer said.

He said the Lotus brand of the analogue clocks was first used by the terror outfit in 2008 for carrying out an attack in Delhi. The make of the bombs was different but the intensity of the improvised explosive devices was low like those exploded in Patna, he told The Telegraph.

An NIA team that visited Assam in the wake of the 2013 Gandhi Maidan (Patna) blasts was informed by a shopkeeper that the manufacturer of Lotus brand clocks had sent a consignment of 300 clocks to Guwahati.