The bank, which was bailed out with 3 billion euros of convertible bonds in 2012, will announce the capital hike "very soon," a source close to the matter said.

“The rights issue can reach about 2 billion euros. (It) can happen very soon,” the source told Reuters.

Final approval from the Portuguese stock market regulator is needed before an announcement is made.

"First, the bank must have the final OK by the regulator (CMVM)," the source added.

The regulator may already be looking at the proposed hike for the bank, which had promised to repay the state fully by early 2017 and sell off key assets including its Romanian business and a fund manager by the end of 2015.

“The CMVM regulator may already be assessing a proposed prospectus for a capital increase of Millennium BCP,” another financial source familiar with the situation told Reuters.

The bank's chief executive confirmed to Reuters last week that the bank was considering a capital hike to help it to repay the state loans faster. He had however said that the bank would conduct a review to see if there was a better alternative to raising capital.

A Millennium BCP spokesman declined to comment.

(Reporting by Sérgio Gonçalves in Lisbon, Sophie Sassard in London; Writing by Tasim Zahid in Bangalore; Editing by Cynthia Osterman)