NEW YORK – Few criminal trials have taken place in the city since the attack on the World Trade Center because the Police Department, stretched to maintain high security, could not free up officers to testify.

That should change this week.

In a sign that the city is inching toward business as usual, the department was ordered to make its officers available to the courts starting yesterday.

Judge Jonathan Lippman, New York state’s chief administrative judge, said some criminal trials that were under way at the time of the Sept. 11 attacks have proceeded, but only a very few have begun since then. Court officials had no firm statistics but estimate that only 10 percent of the normal number of cases been heard since the attack.

In a typical week, court officials say, felony trials would number in the low hundreds citywide.

Prosecutors said the suspension of criminal trials has created slight backlogs, and defense lawyers said it has forced some defendants to stay in jail much longer than they would have otherwise.

“Obviously it’s a problem in that we do have cases that have to be tried right now,” Lippman said. “The cases languish. They back up other cases. We couldn’t go too long without the system buckling.”

The day after the terrorist attacks, Gov. George Pataki issued an executive order suspending speedy-trial rules that compel prosecutors to bring a case by a certain deadline. Unless the governor renews or modifies the order, it will expire Oct. 12.

The suspension of criminal trials was just one aspect of an unprecedented citywide crisis in the wake of the attacks left more than 5,500 dead or missing.

“I don’t think in the 20th century there was any total disruption to municipal government such as there has been as a result of the World Trade Center,” said Thomas Reppetto, an author and expert on New York City police and criminal justice.

The attacks on the trade center have crippled the criminal justice system in many ways.

Many lawyers who were based in the trade center or the immediate area lost their offices and files.

Nearly one in five lawyers in the city was displaced by the blast.

And in Manhattan, the courts and the district attorney’s office, situated just blocks from the twin towers, are still without full phone service. Barbara Thompson, a spokeswoman for Manhattan District Attorney Robert Morgenthau, said phone service was “fragile” yesterday, nearly three weeks after the attacks.

Michele Maxian, who heads the criminal defense division for the Legal Aid Society, said the delay has created “a terrible situation” for jailed defendants awaiting trial. Many of those being held on minor charges would already have had their cases heard – and been released -were it not for the disruption.

“They all say that they understand this but they didn’t cause it,” Maxian said. “They all want to be home with their families as much as we want to be home with our families at this time.”