Red Fort blast: Explosive contained mixture of ammonium nitrate and TATP, shows forensic analysis

The findings are crucial, as investigators are examining a possible link between the Delhi blast and the Faridabad terror module, as part of which 358 kg of ammonium nitrate and other bomb-making materials have been seized.

Ammonium nitrate, commonly used as agricultural manure, is legally sold only through registered vendors. Experts told The Indian Express that while the chemical has legitimate uses in fertiliser and certain industrial processes, its storage and sale are monitored because of its known potential for misuse.

In Old Delhi’s Tilak Bazar, licensed traders said such chemicals are not stored or sold in the Capital. “The pool of legitimate buyers is already very narrow, and most of them are involved in agricultural or authorised industrial work,” a senior market association member in Delhi said.

Probe so far has revealed that the accused procured the batch of ammonium nitrate and fertilisers from outside the city – from shops at Sohna, Gurgaon and Nuh in Haryana.

Ammonium nitrate has been widely used in terror-related blasts in India, especially before 2012, when it was found in nearly every major attack, including the 1996 and 1997 serial blasts in Delhi. Today, most terror groups rely on IEDs, for which ammonium nitrate remains a key component.

Its access is highly regulated: a district magistrate can permit possession of up to 30 metric tonnes, while larger quantities require PESO (Petroleum and Explosives Safety Organisation) approval. Buyers must state the purpose of use, and the government’s System for Explosive Tracking and Tracing (SETT) monitors all licensed transactions. Despite this, large-scale illegal sales and purchases still persist.

According to an expert, a compound used as an explosive should contain oxygen atoms. Ammonium nitrate has three oxygen atoms, RDX contains many oxygen atoms, and trinitrotoluene (TNT) has nine oxygen atoms. TATP, which is formed from a combination of several chemical compounds, also contains oxygen and can detonate. The accused in the November 10 blast likely created an IED with a detonator by mixing ammonium nitrate and TATP.

Ammonium nitrate, readily available as a fertiliser, can be turned into a powerful explosive when mixed with a fuel oil to create ANFO (Ammonium Nitrate-Fuel Oil). Timothy McVeigh used two tons of ANFO for the 1995 Oklahoma City bombing, killing 168 people. TATP, although unstable, was used in the November 2015 suicide attack in France and by ‘Shoe-Bomber’ Richard Reid in his failed attempt to bomb an aircraft in 2001.

Joint Commissioner of Police (Central Range) Madhur Verma said, “Delhi Police is taking additional preventive steps (to ensure there is no sale of such chemicals)… As a proactive measure, we are convening a meeting with chemical associations and registered vendors, particularly those operating in Tilak Bazaar and other Old Delhi markets.”

The meeting is expected to focus on mapping the chemicals currently being traded, identifying substances that could be misused in making explosives, and strengthening internal checks within the supply chain. “Our aim is to ensure better monitoring and to plug any possible gaps that could aid misuse in future,” Verma said.

Police said they will also examine documentation protocols, stock audits, and communication channels between vendors and enforcement agencies to ensure that unusual or suspicious demand patterns are quickly flagged.