Sabine Lautenschlaeger attends at a news conference at the ECB in Frankfurt October 26, 2014. REUTERS/Ralph Orlowski

FRANKFURT (Reuters) - British-based banks seeking to relocate to the European Union before Britain leaves the bloc are behind schedule in their preparations for the move, a European Central Bank supervisor said on Wednesday.

International banks based in London risk losing access to the EU’s single market once Britain leaves it in 2019, forcing many to consider moving parts of their businesses to the bloc and seek a license from the ECB, the sector’s watchdog.

But Sabine Lautenschlaeger, who represents the ECB’s supervisory arm on the central bank’s board, said progress had been slower than hoped.

“Frankly, the banks are not as far advanced as we would like them to be,” Lautenschlaeger said in a newsletter article.

“Of the banks that have indicated an interest in relocating operations to the euro area, a number of the larger banks have made progress in their planning. But we have not seen many final decisions yet.”

She added the ECB would not grant licenses to “empty shells” and would take a tough stance on “back-to-back transactions”, where a bank would conduct trades out of its EU base but process and risk manage them at its London office.

“While we do not rule out this practice per se, ultimately we expect banks to manage relevant parts of their risks locally and independently,” Lautenschlaeger said.

Lautenschlaeger also said she expected banks moving to the EU to update their recovery plans, which kick in if they fail, “shortly” after moving.