Updated

Barcelona officials emphatically denied a newspaper report claiming United States anti-terrorism officials warned them of a planned attack in the city’s busy tourist center, which ultimately occurred earlier this month -- but Spanish authorities did acknowledge receiving other tips from sources they didn't deem credible.

Catalan regional interior chief Joaquim Forn said Thursday regional police were not warned by the CIA or the National Counterterrorism Center that an attack was imminent on Las Ramblas, the Barcelona tourist district, adding that such warnings would be made through state channels.

He said other warnings they received about possible attacks throughout the city were not related to the Aug. 17 van attack that left 14 dead and dozens injured. One other person was stabbed to death by the Barcelona attacker as he fled. Another attack in nearby Cambrils left 1 dead.

Barcelona-based El Periodico newspaper reported Thursday morning that the U.S. sent a warning May 25 to regional police, specifically mentioning an attack on Las Ramblas.

The alleged warning read: "<<INTELLIGENCE PURPOSES ONLY: This information is provided only for intelligence purposes in an effort to develop potential investigative leads. It may not be used in any way that will expose or jeopardize intelligence sources or methods. It cannot be used in connection with any foreign or domestic court proceedings or for any other legal, judicial, or administrative purposes.

(S//REL TO SPAIN) Unsubstantiated information of unknown veracity from late May 2017 indicated that the Islamic State of Irak and ash-Sham (ISIS) was planning to conduct unspecified terrorist attacks during the summer against crowded tourist sites in Barcelona, Spain specifically, La Rambla Street.>>"

Forn slammed the report as “irresponsible” and claimed the newspaper was trying to discredit the work of regional security forces los Mossos d’Esquadra.

“The document is a montage that the director of the newspaper acknowledges, made through information he says he has received,” he said. “For us, this is a very serious event. The Mossos receive dozens of terror warnings and all are contrasted to learn the credibility they might have.”

On Twitter, the alleged warning was also slammed by the likes of WikiLeaks leader Julian Assange, who said it appeared to be “modified or fabricated.”

“The use of Spanish language quote marks ‘<<’, ‘>>’ in an English CIA report is very suspicious,” he wrote.

Wikileaks added the use of ISIS, which is used by the media, instead of ISIL, which has largely been used by intelligence forces, and the Spanish-language spelling of Irak, instead of Iraq, also made the group doubt the authenticity of the document.

WikiLeaks then tweeted the newspaper's editor admitted to creating the document, saying it is "a transcription of what was told to them over the phone."

The U.S. embassy in Madrid said it could not comment on intelligence issues.

The Associated Press contributed to this report.