Indian police said on Thursday they were taking seriously a specific US warning of possible attacks on New Delhi shopping centers, an alert that underlines challenges for a city hosting the Commonwealth Games in October. Threats to sporting events were underscored last week when bombs exploded outside a packed cricket stadium in south India, stirring fears the country may not be able to secure multi-city events involving tens of thousands of players and spectators. India is also holding next year's cricket World Cup across eight cities. The US advisory issued on Wednesday spoke of “increased indication that terrorists” are planning to attack some of New Delhi's markets frequented by foreigners. Some of these markets have been bombed in the past. “Every bit of input is important. We are in a permanent state of alertness, but when we have a specific input we sensitize our staff to any special security needs,” said Rajan Bhagat, spokesman for Delhi Police. Police say the alert underscored their suspicion that security at Games venues may prompt militants to turn to softer targets. Officials said the basis of the US travel alert was intercepted telephonic messages of Pakistan-based militant groups. “We are aware of the nature of the inputs the US State Department has,” said UK Bansal, a senior Interior Ministry official. New Delhi and other Indian cities are already on high alert, but the specific nature of the US advisory prompted the authorities to hold several security review meetings on Thursday. Australia and Britain have also issued travel advisories for India. Security agencies routinely intercept messages exchanged between militant networks, but officials said the highly detailed alert had prompted immediate action, including tighter security. “We had part of this alert already, and now with the US alert we have activated our forces further, especially in markets,” special police commissioner Neeraj Kumar said. India raised security in the aftermath of a bombing that killed 17 people in western India in February, the first major attack in the country since the 2008 Mumbai attacks that killed 166 people. Meanwhile, Australia and Britain on Thursday warned tourists of the increased risk of militant attacks in New Delhi, joining Canada and the US, which have urged foreigners to avoid parts of the Indian capital. The United States said Wednesday it had information of a “specific” threat to half-a-dozen of the city's shopping areas and markets which it described as “especially attractive targets.” The Canadian government said on its website that an attack could be carried out “in the following days or weeks in market areas” of Delhi frequented by foreigners, specifically in the Chandni Chowk area in Old Delhi.