Imphal, Jan. 25: Serial blasts at different places shook the security establishment here today, on the eve of Republic Day.

The explosion of three improvised explosive devices (IEDs) within a span of four hours did not cause any casualty or injury. But one of them took place at the 1st Manipur Rifles complex, where the parade ground is located. The blasts induced a flurry of activities in the security agencies although no outfit has claimed responsibility for the blasts so far.

Director-general of police Yumnam Joykumar Singh said militants exploded IEDs just to "show their capabilities, not to cause mass destruction. They were low intensity bombs. There was no casualty or damage."

The first blast took place near the storeroom of the 1st Manipur Rifles battalion headquarters in the heart of Imphal at 7.30am. The site of the blast is a little over 100 metres south of the parade ground.

The second explosion occurred two hours later on the bank of the Nambul river in Keishamthong, about half-a-km from the first site. Forty-five minutes later, the third bomb exploded near the gate of Raja Dumbra School in Imphal East. Police suspect the hand of insiders in the first blast.

"We suspect the hand of insiders in the Manipur Rifles complex blast. It was planted last night. However, we cannot say with certainty at the moment, as we don't have any evidence. We are looking into it," Joykumar Singh said. A senior police officer told this correspondent that the bombs were exploded with timer devices.

Deputy chief minister Gaikhangam, who is also the home minister, asked the police to probe the Manipur Rifles complex blast to find out if any "inside hand" was involved. "The blast could not have taken place without the involvement of someone who knows the area well," Gaikhangam told reporters on the sidelines of a function here. He said the serial blasts "just show the existence of militants" and the government would not allow them to put a spanner in the Republic Day celebrations.

Many people were present inside the Manipur Rifles complex since last afternoon, constructing tableaux and gates for tomorrow's marchpast.

After the blast, senior police officials rushed to the complex and verified the safety of all those present near the site. A search was also launched but no one was arrested.

The entry of people was restricted at the parade venue after the blast. Mediapersons were also not allowed to enter the blast site. However, no action was taken against the sentries for their alleged lapse in vigil. Joykumar Singh has directed authorities of the 1st Manipur Rifles not to allow relatives of jawans or army officers to stay at the family lines inside the complex following today's incident.

Following the blasts, security measures were tightened. Police bomb squads searched the marchpast route and no vehicle or two-wheelers were allowed to park along the route.

Contingents will start marching at the parade ground tomorrow after passing through Imphal streets. Governor Gurbachan Jagat will take the salute from the contingents inside Kangla fort. Chief minister Ibobi Singh will address the gathering once the contingents gather there. CorCom, a coordination committee of seven militant groups of Manipur, is boycotting the Republic Day celebrations and has called a daylong statewide general strike tomorrow.