Spain received a warning in May that the Islamic State group was planning an attack in Barcelona but decided it lacked credibility, Catalan regional authorities said Thursday.
But they denied news reports that US security agencies were behind the warning of an attack targeting the city, where the jihadists claimed a deadly van rampage two weeks ago.
The daily El Periodico de Cataluna reported that the US National Counterterrorism Center (NCTC) had alerted Spanish intelligence officers to the threat weeks before a man ploughed his van into crowds of tourists along Barcelona's Las Ramblas boulevard on August 17, killing 14 people.
"Unsubstantiated information of unknown veracity from late May 2017 indicated that the Islamic State of Irak and ash-Sham (ISIS) was planning to conducted unspecified terrorist attacks during the summer against crowded tourist sites in Barcelona, Spain, specifically La Rambla street," according to what the paper claims was an NCTC briefing note dated May 25.
The note is a transcription, and not the original, which explains why it has several spelling mistakes, the newspaper's director Enric Hernandez said.
But the regional Catalan government's interior minister, Joquim Forn, dismissed the note as a "composite".
"The warning regarding a possible attack in the summer in places such as Las Ramblas reached us from other sources," he told a news conference without giving further details.
After analysing the information in the warning, and sharing it with Spain's central government, Spanish authorities concluded the "warning had very little credibility," he added.
There is "absolutely no link between this information" and the van attack in Barcelona on August 17, he said.
The head of Catalonia's regional police, Josep Lluis Trapero, said the warning did not come from the CIA or the NCTC.
A spokesman for Spain's CNI intelligence agency, contacted by AFP, refused to "confirm or deny anything on communication with other intelligence services".
The interior ministry did not respond to a request for comment.
But the Madrid-based Cadena SER radio station quoted "anti-terror sources" suggesting that the document published by El Periodico de Cataluna was authentic.
Spain is still recovering from the twin August vehicle attacks that left a total of 16 people dead and more than 120 wounded in Barcelona and the seaside resort of Cambrils further south.
IS claimed both attacks.