UPDATE 1-Britain asks Spain for more details on European arrest warrant for Catalan separatist

(Adds Spanish government comment on change to Britain stance)

MADRID, Nov 6 (Reuters) - Britain has put on hold a Spanish request to extradite Catalan separatist Clara Ponsati over her role in a failed independence bid and demanded more information, according to British documents published by Spanish authorities.

In an initial document sent to the Spanish Interior Ministry on Wednesday and seen by Reuters in Madrid, British police deemed the warrant "disproportionate under UK law."

However, acting Spanish Foreign Minister Josep Borrell on Wednesday night said on Twitter that British police had "corrected their use of the term disproportionate" to refer to Ponsati's extradition request.

"Their new communication clarifies that it is simply about asking for more information," Borrell wrote on Twitter.

He linked to a document also published by the Spanish government, that it said came from UK authorities, in which Britain clarified the misunderstanding.

"In our previous message ... our reply incorrectly stated that the warrant was disproportionate - it is not disproportionate, it is just currently lacking in essential information," it said.

Spain's Supreme Court on Tuesday reactivated a European arrest warrant for Ponsati, who currently lives in self-imposed exile in Scotland, and two other former Catalan leaders in Belgium for helping to organise a 2017 referendum deemed illegal by a Spanish court. The plebiscite set off a short-lived declaration of independence in Catalonia.

Ponsati is facing one charge of sedition, according to court documents issued in Spain, the same charge for which various independence leaders were sentenced in October to up to 13 years in prison.

Catalan separatism is a sensitive issue in Spain, especially four days before a general election in which it could play an important role. (Reporting by Emma Pinedo, Ashifa Kassam in Madrid and Guy Faulconbridge in London; Writing by Jessica Jones; Editing Ingrid Melander, Giles Elgood and Bill Berkrot)