India will offer all possible assistance to neighbouring Sri Lanka in probing ghastly terror attacks that rocked the island on Sunday and handling aftermath of the strikes that killed over 200, even as allegations including role of Islamic State and revenge for New Zealand mosques flew thick and fast over the motive behind return of terror to Colombo after a decade.The serial terror attacks, one of the worst in South Asia, sent alarm bells ringing in Delhi which in the past grappled with civil war in Lanka until it came to close in 2009. Sources here claimed that this is a typical Islamic State attack – way the blasts have been synchronised and orchestrated. The Modi government is working closely with Lanka on the matter, sources indicated.The Islamic State is suspected because of the nature of the attack, but thorough probe is required on type of explosive used, and the kind of detonator used. The sites of the attack – churches – was chosen to attract international attention. A coordinated blast on Easter will have huge global impact.While Sri Lanka has a history of LTTE-led terror sources here described it as a matter of the past and alleged that a local module of ISIS seeking revenge for the New Zealand mosque attack could be behind Sunday’s episode. LeT has also been trying to recruit for past few years, sources alleged.There are also reports that the NTJ (National Thowheeth Jama'ath) was planning to carry out suicide attacks targeting prominent churches as well as the Indian high commission in Colombo earlier this month. The High Commission is located a prime location in Colombo and close to sea front. NTJ is a radical Muslim group in Sri Lanka that came to notice last year when it was linked to the vandalization of Buddhist statues.While Indian officials and security experts were engaged in brainstorming on motive and group behind the attack in the key neighbouring state, several other conspiracy theories are doing rounds. Colombo based sources alleged that Buddhist-Christian tensions have been simmering over reports of conversion and the attack could be a fallout of that. Other allege that Opposition could be behind the attack to discredit PM Ranil Wickremasinghe.Amid his hectic election schedule Prime Minister Narendra Modi held telephonic conversations with the Lankan President and the Prime Minister and “conveyed heart-felt condolences on his own behalf and on behalf of all Indians at the loss of over one hundred and fifty innocent lives in today’s terrorist attacks in Sri Lanka”.The PM spoke to the SL leadership while he was himself travelling for his political campaignIn fact the PM spoke to the Sri Lankan President, even as the Sri Lankan President is currently in Singapore.Modi condemned in the strongest terms the serial terrorist attacks, perpetrated at sites including religious places and during a religious festival, according to a government statement. Terming them as cold-blooded and pre-planned barbaric acts, he pointed out that these “attacks were another grim reminder of the most serious challenge posed to the entire humanity by terrorism in our region and the entire world.”The PM has offered all possible help and assistance to Sri Lanka for ensuring its security against the challenges such as those posed by terrorism. He also offered any required assistance for treatment of the injured as the island nation grappled with the number of injured.The Indian High Commission stated it is closely monitoring the situation. "Explosions have been reported in Colombo and Batticaloa today. We are closely monitoring the situation," the High Commission of India said in a Tweet.“India has always opposed and rejected terrorism in all its forms and manifestations, and has urged concerted action by the international community against terrorism, including cross-border terrorism. There can be no justification whatsoever for any act of terror. We call for perpetrators of such ghastly and heinous act and those who provide them support to be brought to justice expeditiously,” MEA noted in a statement within hours of the serial terror strikes reminiscent of 26/11.