Several big U.S. banks, including Pittsburgh-based PNC Financial Services Group, have asked the federal government to take action to stop cyber attacks against their websites, according to a story Wednesday in the Wall Street Journal.

Like a handful of other major banks, PNC has been pummeled in recent months with denial-of-service attacks that have slowed its website and prevented some customers from accessing their accounts.

The attacks work by flooding websites with communications requests.

U.S. Defense Department officials have blamed Iran for the attacks, while the Iranian government has strongly denied any involvement. A hacking network has claimed responsibility in Internet posts, saying the attacks will continue until an online video insulting to the Islamic Prophet Muhammad is removed.

Officials from the White House, Federal Bureau of Investigation and other U.S. agencies have been in discussions with the affected banks and have been weighing options, including possible retaliation against Iran, the Journal article said, citing unnamed investigators and government officials.

A number of affected banks would like the government to block the attacks or disable the network of computers behind the assault, the newspaper said, citing unnamed bank officials.

Some bank officials have argued against any retaliation or pursuit of the hackers, saying it could lead to additional attacks, the Journal said.

PNC spokeswoman Marcey Zwiebel on Wednesday declined to say whether PNC had asked the government to step in.

So far, the attacks, which have been a major inconvenience for some customers, have not compromised any financial data, PNC has said.

"Most of our customers have not experienced any access issues," Ms. Zwiebel said Wednesday. "For those who are, we are working with them individually to help them through it."