Action has already been taken to deny Department of Justice funds to sanctuary cities whose leaders refuse to cooperate to immigration officials, and President-elect Donald Trump can cut off their money on his first day in office, and require some to repay billions of dollars of assistance they have already received, Rep. John Culberson, R-Texas, said Wednesday.

"Using existing law and the power of the purse, I have seen to it that the top 10 sanctuary cities in America have already been certified as violating existing federal law," Culberson, who chairs the House Appropriations subcommittee overseeing the DOJ, told Fox News' "America's Newsroom."

"Everything is pre-positioned for these 10 cities, including Chicago, New York, the entire state of California," the lawmaker continued. "They will lose all their federal law enforcement money if President Trump chooses to.

"The president can cut off their money on Jan. 20 if they do not hand over criminal illegal aliens in their custody."

The Illegal Immigration Reform and Immigrant Responsibility Act of 1996, passed during former President Bill Clinton's administration, can be called into play, Culberson said, which requires cities to comply with immigration officials or lose their federal funding.

Culberson said as chairman of the subcommittee in charge of DOJ funds, he "quietly persuaded" Attorney General Loretta Lynch to implement the policy.

In February, Culberson penned a letter to Lynch demanding she includes a promise to comply with federal laws, including cooperation with Immigration and Customs Agents when cities apply for Byrne Justice Assistance Grants — the community-oriented police office assistance program — and the State Criminal Alien Assistance Program.

If Lynch had not agreed, the DOJ could have faced consequences when Congress wrote its 2017 spending bill, Culberson said at the time.

The representative told Fox News on Wednesday that Lynch has notified the sanctuary cities of of the issue, which was resolved in July, and Trump can immediately act on it, as the policy is ready to go.

"The Department of Justice notified the cities, unless you change your sanctuary cities and comply with federal law all the time, you are no longer eligible [for funds]," Culberson said.

"And if you continue to defy and get rid of your sanctuary policies, they will owe a refund every dollar they ever received from the federal government under these Department of Justice programs. And these are minimum figures.

"The state of California, if they will not change their law will owe taxpayers $1.2 billion. The city of Chicago will have to write a refund check to American taxpayers for $91 million, and New York City Mayor [Bill] de Blasio, you get to choose between protecting illegal aliens in your custody or refunding the money."

And if city leaders want to protect "criminal illegal aliens" then that is their decision, Culberson said.

"If you want to protect criminal aliens, don't ask for federal money," he said. "Those days are over. If you don't change your policy, you will have to write us a refund check. That will get their attention."