ALAN CLENDENNINGMADRID (AP) â¿¿ Spanish banks must raise an additional euro50 billion ($65.5 billion) to cover their exposure to toxic real estate loans and assets accumulated during a construction boom that went bust with the financial crisis, according to new regulations unveiled Thursday. Banks unable to meet the new provisions to cover troubled holdings will have the option of presenting merger plans to the government by May and could get government assistance from an existing bailout fund that will be strengthened with an addition euro6 billion, said Economy Minister Luis de Guindos. Cleaning up the festering holdings of Spain's ailing banking system is a key issue in the drive by the new center-right government to restore investor confidence in the eurozone's fourth largest economy, and prevent Spain from being forced into a bailout like Greece, Ireland and Portugal were forced to take. Banks that want to meet the new provisions without merging will have until the end of the year to do so, de Guindos said. Spanish banks have about euro175 billion in troubled holdings, and de Guindos said the new rules would prompt many banks to reduce the value of their property holdings. That would lead to further price drops for real estate that saw stunning increases from the mid-1990s until the crisis hit in 2008 but still have not declined as much as experts believe they should. The reform plan is similar to a 2009 push that forced banks to increase provisions against real estate holdings and bad loans to 30 percent and set off a wave of mergers, but de Guindos said the new rules to protect banks from losses will boost that figure to as much as 80 percent. The cabinet of Prime Minister Mariano Rajoy plans to approve the measures Friday. They will be sent to Parliament for final approval, but passage is guaranteed because Rajoy's Popular Party has an absolute majority.