The faction in the Turkish army that tried to stage a coup was under investigation before the actual incident took place, and most likely acted out of a growing fear that it was under investigation, according to two Turkish officials.

At least 290 people died and thousands of civilian and military state employees were sacked or detained after rebel soldiers attempted to overthrow the government on Friday, bombing state buildings, including the parliament, and killing civilians and security forces.

The government and President Recep Tayyip Erdogan blame US-based Muslim religious leader Fethullah Gulen's movement and his supporters within the army for trying to stage the failed coup.

Ankara says the movement has been running "a parallel state" within Turkey's government, taking orders from outside the state.

Erdogan has urged Washington to extradite Gulen, but the US denies that there has been an official application from Ankara for his extradition.

According to Kani Torun, an MP with Turkey's Justice and Development Party, an investigation into the faction was initiated as a follow-up to so-called espionage and sledgehammer cases, during which hundreds of military personnel were acquitted after standing trial for plotting against the government.

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During both cases, tried army members were known to point at Gulen supporters within the army and the wider state institutions, including the judiciary.

"The putschists were to be called by prosecutors and arrested by the courts a short time before they carried out their attempted coup," Torun told Al Jazeera.

"We believe they moved their attempt to an unusual time such as 10pm in the evening after they heard about this upcoming development. If they carried it out in the morning as planned, they would have had more chance of success."

'A very long shot'

An official, who asked to remain anonymous, seconded the information Torun shared, saying that for the past several months Turkish authorities had been looking into people who were suspected of conspiring to stage a coup within the military, but a real potential coup was considered "a very long shot".

"Known members of the Gulen Movement within the military had been under investigation for some time. In our assessment, this group acted out of a sense of emergency when they realised that they were under investigation," he said.

He added that the Gulen Movement is a very secretive and large organisation, operating cells across the government that make it hard to detect.

"The chain of command is not hierarchical within individual institutions, but cells typically include members from various agencies ... What we did realise was unusual activity across the network. But I don't think an actual coup d'etat was considered likely in pre-July 15 assessments."

Since the attempted coup, the government has cracked down on suspected backers of the plan to topple the civilian government. As of Monday night, more than 8,000 people had been arrested over alleged involvement in the failed coup.

Kani Torun told Al Jazeera that judiciary, military, and police forces were the main target of the crackdown on the Gulen movement, but operations were likely to spill over into other institutions.

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"State institutions involved with defence industry and TUBITAK [national agency with stated goal of developing science, technology and innovation policies] have also been infiltrated by them," he told Al Jazeera, adding that "spot operations" will continue for seven to 10 days.

Torun also warned that the coup supporters, who have left with no hope and are still at loose, might carry out "revenge attacks" just to create chaos.

"I can say there are at least several dozen people at large," Turkish official, who asked to stay anonymous, told Al Jazeera.

"Our concern is that, without the necessary precautions, there might be new attacks on government buildings and civilians by members of the failed junta. Hence the call on people to stay at public squares and road blocks in Ankara around the parliament and other places," he said.