The Ministry of Home Affairs has issued an alert to all states and security agencies after intelligence agencies warned of possible terror attacks on aircraft, at metro stations or other modes of public transport, The Times of India reported. The Centre has asked all security agencies to step up frisking and baggage checks at airports, bus stands, and train and metro stations.

“Central security agencies have intimated that terrorists are planning a range of attacks against commercial aviation targets,” stated the advisory, dated September 1, according to India Today. “Recent intelligence inputs are indicative of threats from explosives concealed inside a personal electronics or small appliance and other personal items. Such items could be taken on a plane or shipped by airmail.”

The ministry is also believed to have asked the security agencies to be on the lookout for any substance that could release toxic gas. “Toxic gases pose the greatest hazard when made in an enclosed space, underscoring the risk to aircraft, buses or trains,” it stated.

Referring to a foiled terror attack bid in Australia to blow up an aircraft in August, the MHA said it underscored the focus of such groups on devising innovative ways to attack various modes of transportation. The letter also said that “terrorists remain interested in small arm attacks and physical assaults on airports and other transportation hubs.”