Foreign Secretary Boris Johnson has rejected calls for the UK to intervene with the Spanish government over the police crackdown against Catalonia's independence referendum.

The move came after security forces used rubber bullets and baton charges as they clashed with protesters, leaving more than 1000 people injured, according to Catalan health officials.

The Spanish National Police and Civil Guard moved to shut down the vote which is backed by the Catalan regional authorities.

READ MORE: Voting closes in Catalonia after shameful day of violence by Spanish police leaves 761 people injured

First Minister Nicola Sturgeon had slammed the UK Foreign Office's response to the situation, a brief statement which did not even mention, let alone condemn, the violence carried out by Spanish police on peaceful voters.

She tweeted: "Statement from @foreignoffice on #Catalonia is shamefully weak. A true friend of Spain would tell them today’s actions wrong and damaging."

Johnson then personally took to Twitter to insist the situation was something for Spain to deal with. He tweeted: "The Catalonian referendum is a matter for the Spanish govt & people.

"Imp that Spanish constitution respected & rule of law upheld.

"Spain is a close ally and a good friend, whose strength and unity matters to the UK."

READ MORE: More than 1000 Scots gather to show support for Catalonia

His cabinet colleague and International Trade Secretary Liam Fox had condemned the violence in Catalonia but said the Spanish government has a "right to uphold the law".

Fox, who has travelled to region regularly since 1968, said: "It's quite tragic to see it."

He said: "It's a matter for the government of Spain. They view the referendum as being illegal and they have a right to uphold the law.

"But, of course, counterbalanced against that is the right to self-determination of peoples and how they deal with that is a matter for them. All I would say is that in the United Kingdom we were willing to take on the argument of the separatists in Scotland on and we were able to defeat those arguments by pointing out the benefits of the union."

He added: "We must regret the sort of violence we have seen. I think we would all condemn the violence but we need to understand the government of Spain has a constitutional view about its integrity as a state."