Moody’s Investor Service on Monday cut its credit ratings on 28 Spanish banks, saying the weakening financial condition of Spain’s government is making it more difficult for that country to support its lenders.

The banks are also vulnerable to losses from Spain’s busted real estate bubble, Moody’s said.

The announcement from Moody’s came on the same day that Spain’s government formally asked for help from its European neighbors in cleaning up its stricken banking sector. However, the request left many questions unanswered, including how much Spain will ask for out of the $125 billion loan package it has been offered.

That uncertainty led to losses in stock markets in Europe and the United States. Bond investors pushed Spain’s borrowing costs higher, a sign of wilting confidence in the country’s ability to support its banks.

The downgrades reflect Moody’s view on the ability of the 28 banks to repay their debts. Moody’s said the lower ratings stemmed from its having downgraded the Spanish government’s credit rating by three notches earlier this month.

Among the lenders suffering rating cuts were Spain’s two biggest international banks: Banco Santander and Banco Bilbao Vizcaya Argentaria.

A downgrade usually means that banks will have to pay more to service their debt. Investors demand higher interest for riskier debt, which is what the downgrades represent.

Spain formally asked the European Union on Monday for rescue loans to help clean up its troubled banking industry. The Spanish economy, the fourth-largest of the 17 countries that use the euro currency, is suffering from the aftershocks of a real estate bust that has devastated families and banks.