"As we face the departure of the largest EU financial centre, we committed to stepping up our efforts to further strengthen and integrate the EU capital markets," European Commission Vice President Valdis Dombrovskis said on Thursday.

Europe's capital markets union (CMU) was launched in September 2015 to improve the way stock and bond markets support growth, and offer companies alternatives to bank loans.

The aim is to put the "building blocks" in place by 2019, but as this now coincides with Britain leaving the EU, the bloc needs to also reduce its dependence on London.

"Quick wins" such as reviving securitisation or asset-backed debt, and making it easier for companies to list - two of the 20 measures passed from an original list of 33, have already taken longer than expected to win parliamentary approval.

And in its "mid-term" review of the CMU for an EU of 27 countries, the Commission listed nine more "priority actions", including direct supervisory powers for the EU's securities watchdog and helping banks to offload bad loans.

However, Jyrki Katainen, European Commission Vice President for jobs, growth and investment, said it could take up to a decade to see results from the CMU initiatives.

"It's a question of whether this potential is used or not," Katainen told a news conference.

Markus Ferber, vice chairman of the European Parliament's economic affairs committee, called the review a "document of failure" that listed what has still not been accomplished.

"In light of Brexit, effective and efficient European capital markets are more important than ever. Instead of devising new updates of their working plans every few years, now would be a good time for the Commission to actually make some progress," Ferber said.

Peter Green, a financial lawyer at Morrison & Foerster, said it was questionable whether the reboot was enough to create an effective rival market to London.

A big test will be how much progress Brussels can make in helping banks to offload bad loans, a problem that led this week to European authorities intervening to avoid a collapse of Spain's Banco Popular.

Bad loans can restrict banks' ability to lend, but shedding them is hampered by high transaction costs.

The EU executive will soon launch a consultation on action in areas such as loan servicing by third parties, and the transfer of loans, including to non-bank entities.

(Editing by Jane Merriman and Alexander Smith)

By Huw Jones