LONDON (Reuters) - A newspaper report that British Prime Minister Theresa May is preparing to offer up to 20 billion pounds more to the European Union as part of Brexit divorce bill is speculation, her spokesman said on Thursday. The EU has told Britain to spell out what it will pay when it leaves the bloc in 2019 or it may miss a deadline next month to move the talks to a discussion of future trade ties, which businesses say is vital for them to make investment decisions.  We want to make progress as quickly as possible and we want to move onto talks about the future relationship as quickly as possible,  the spokesman said. Of the 20 billion pounds report he added:  I would say it is yet more speculation.  