Trump and Putin
A woman walks past a mural of President Donald Trump and Russian President Vladimir Putin in Belgrade, Serbia, Dec.4, 2016. The text on the mural reads in Russian, Serbia and English "Kosovo is Serbia." REUTERS/Marko Djurica

British spy agencies alerted their U.S. counterparts in 2015 about contacts between President Donald Trump’s election campaign and Russian intelligence authorities, the Guardian reported Thursday, citing sources. The response from Washington over the alleged contacts was, however, slow, sources told the British daily.

Britain’s Government Communications Headquarters (GCHQ) passed on the information about contacts between Trump’s team and known or suspected Russian agents as part of routine exchange of intelligence, the Guardian reported. Until 2016, spy agencies from Germany, Estonia, France, the Netherlands and Poland also alerted the U.S. about the links between the two sides, sources told the newspaper.

However, the FBI and the CIA responded slowly to the intelligence they were given ahead of the presidential election last November. This was partly because of the U.S. law that prohibits American intelligence agencies to keep a check on the private communications of U.S. citizens without warrants, people familiar with the matter told the Guardian.

“It looks like the [U.S.] agencies were asleep. They [the European agencies] were saying ‘There are contacts going on between people close to Trump and people we believe are Russian intelligence agents. You should be wary of this,’” a source told the Guardian

“The message was: ‘Watch out. There’s something not right here,’” the source reportedly added.

The Guardian report noted that the intelligence on Trump team’s contacts with Russia came to light during routine surveillance of Russian operatives. The Trump campaign team was not spied on.

Last month, White House Press Secretary Sean Spicer cited Fox News commentator Andrew Napolitano who claimed three intelligence sources told him the Barack Obama administration used GCHQ to spy on Trump ahead of the 2016 election. The British agency dismissed the allegation and called the claim “nonsense” and “utterly ridiculous.”

“I don’t want to get into private conversations, but we’ve made clear to the administration that these claims are ridiculous and should be ignored,” a Downing Street spokesman said at the time. “We’ve received assurances these allegations won’t be repeated. We have a close relationship which allows us to raise concerns when they arise, as was true in this case. This shows the administration doesn’t give the allegations any credence.”

However, the White House did not apologize for the allegation and Trump said his administration merely quoted “a certain very talented legal mind who was the one responsible for saying that on television.”