Bank of America Corp. imposed a nationwide moratorium on foreclosures and the sale of foreclosed homes after it came under intense pressure from a government-run housing-finance giant worried about documentation problems, people familiar with the situation said.

The bank called the halt as concern mounted from legislators and state prosecutors about procedures used by lenders to foreclose on homes. Many banks use so-called robo signers, employees who sign hundreds of documents a day, without carefully reviewing their contents, when foreclosing on homes. Critics say that could result in improper foreclosures.

Freddie Mac, the government-run mortgage-finance company that along with Fannie Mae owns many of the mortgages serviced by banks, pressed Bank of America to expand its search for problems with the foreclosure documentation process, said the people familiar with the situation.

On a call Thursday with several banks that included Bank of America, a Freddie official said the mortgage company wanted the institutions to look at foreclosure documentation across all 50 states, and asked them to consider putting a stop to the entire foreclosure process, say people familiar with the call.

Many in the banking industry fear that the widening paperwork problem could cause further delay on foreclosures and threaten an already weak housing market, which in turn is stalling the broader U.S. economic recovery. On the other hand, it could provide a brief financial respite to people who have defaulted on their mortgages and are still occupying their homes.