Mario Draghi, the European Central Bank president, urged member states to consider all options for boosting investment.
The UK, the Netherlands and seven other member states have been asked for extra payments. Why?
Italy's prime minister, Matteo Renzi, says Italy could find the extra money "tomorrow morning" if needed, and defends publication of a confidential letter from the Commission.
Italy lost some €46bn in unpaid VAT in 2012, equivalent to its entire government spending deficit.
The ECB will announce on Sunday the results of its comprehensive assessment of banks' balance sheets, with the hope of restoring confidence in the banking sector and kick-starting lending.