Spanish daily ABC reported in a front-page story on Saturday that the Catalan Government had attempted to acquire 850 military-grade weapons and 5.4 million rounds of ammunition for the Catalan Police (Mossos) in 2016 and had refused to explain to the Spanish Ministry of Defence why they wanted them.

Unnamed Spanish MoD sources cited by the newspaper said the request, made on October 31 last year, was "extremely high" compared to other policing requests for better weapons to deal with terrorist threats, and "raised alarms" at the Ministry of Defence.

The request was for 300 9mm submachine guns, 400 5.56mm Heckler & Koch G36 rifles, 50 Lapua .338 MAG sniper rifles, 50 .300 Whisper and 50 7.62mm rifles, five million 9mm submachine-gun rounds, 400,000 5.56mm rounds, and 20,000 rounds each for the high-precision rifles.

The MoD sent the Catalan regional interior ministry a note on December 12 to request an explanation of why they wanted to acquire the weapons, "but we never received a reply".

The newspaper describes this type of weapons as "very effective" against the recent spate of jihadi terror attacks, but that it was the quantity, not the type, of weapons that set alarm bells ringing at the MoD, along with the lack of a reply.

In 2015, the Catalan government did not request any new weapons; in 2014, it requested 200 9mm submachine guns and 50 5.56mm rifles; the Basque Police (Ertzaintza) requested 27 new 9mm submachine guns and 11 new 5.56mm rifles after an ETA attack at Madrid's Barajas airport in 2006.

Several dozen new pistols of different calibres were also requested, but did not raise any suspicions.

On September 14, the regional interior minister in Catalonia, Joaquim Forn, accused the central government of withholding a shipment of 1,000 weapons for anti-terrorist use, a situation he described as "inexplicable".

Catalan radio station RAC1 published copies of the letters sent between Mr. Forn's predecessor, Jordi Jané, to the Secretary of State for Security at the Home Office last year.

In April, El Confidencial reported the Catalan government had also tried to acquire up to 500 hand grenades, but the German manufacturer warned the central government that the order had been placed.

Madrid eventually authorised the purchase of 500 lower-intensity stun grenades, without the same explosive charge or blast potential the Catalan government had initially requested.