New Delhi says the issue of granting visa to David Headley, US born citizen of Pakistani origin, allegedly involved in the Mumbai terror plot, by Indian Consulate in Chicago without Home Ministry's clearance is being looked into carefully.<br/>The External Affairs Minister Mr. S.M. Krishna told reporters that the issue of the visit of his Canadian accomplice Tahawwur Rehman Rana to various Indian cities is also being probed. Sources say, Centre has evidence that Headley and his Canadian accomplice were in Pakistan, the day Mumbai carnage took place last year.<br/>The investigating agencies are now studying the transcripts of intercepted telephone calls between the Mumbai attackers and their handlers in Pakistan to establish Headley and his accomplice’s links to the terror attack.<br/>The Centre has asked the states to beef up security at nuclear installations across the country following intelligence reports about a possible terror strike. Centre has already made it clear that nuclear installations are safe and secure as multiple levels of security have been put in place.<br/>In a related devolpment Police have identified two central Delhi cyber cafes visited by suspected LeT operative David Headley during his three-day stay in the national capital early this year. Police sources said that it has intensified checkings at cyber cafes in central Delhi's Paharganj, which is continuing on Tuesday also. A senior police official said they have identified two cyber cafes visited by Headley during his three day stay in two hotels in Paharganj in March this year. He said, the information has been passed to National Investigation Agency.<br/>US terror suspect David Coleman Headly had visited Pune twice. The investigations have reveled that he had visited prior and after to Mumbai terror attack. A team of National intelligence agency which recently came to Pune said it had found that Headly had stayed in Osho Ashram. Police are collecting more information on his stay in the city. <br/>The National Investigation Agency (NIA) is scrutinising the documents and other details collected by the Mumbai Crime Branch during its local probe in US terror suspect David Headley's Mumbai links.<br/>NIA officials, investigating Headley's connection with the 26/11 terror plot, have visited the places where Headley stayed to get a first-hand experience of the facts. Headley had spent much of his time in India between 2006 and 2009 and, in Mumbai, stayed at a rented flat at Breach Candy and ran an immigration business from the Tardeo AC Market.<br/>He came on a business visa. More than 20 teams of sleuth of NIA are probing Headley-Rana trail and central security agencies have been formed for gathering information about the places the duo had visited between 2006 and 2009. NIA officials, probing Headley’s connection with the 26/11 Mumbai terror plot are likely to question Ajmal Kasab, the lone surviving terrorist.<br/>Meanwhile, Maharashtra Home Minister RR Patil said that the state would extend full support country's top agency to probe the role of Headley and Rana in the Mumbai terror attacks. However Mr. Patil said that NIA has not approached Maharashtra Govt to question Kasab.<br/>