Lawyers for Dzhokhar Tsarnaev, the alleged Boston Marathon bomber, have again asked a federal judge to lift special prison restrictions that have been placed on him, saying the restrictions have allowed the FBI to monitor their defense preparations.

The lawyers alleged in a court filing Thursday that the FBI has been monitoring the case and the Bureau of Prisons has attempted to screen digital documents that they have brought to prison to review with Tsarnaev, in violation of his constitutional rights to prepare his case without government interference.

“These obstacles thwart preparation of important parts of the defense case … and also threaten the integrity of attorney work product,” the lawyers said, adding that the US Supreme Court has agreed that a defendant’s rights to lawyers “grants attorneys a zone of privacy within which to prepare the client’s case and plan strategy, without undue interference.”

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Federal prosecutors did not immediately respond to the defense team’s complaint.

The defense lawyers first asked US District Court Judge George A. O’Toole Jr. in October to ease the tight restrictions, called Special Administrative Measures, that have been placed on Tsarnaev at the federal prison at Fort Devens in Ayer, where he is being held. They argued that restrictions such as excessive monitoring of documents and limitations on who can visit Tsarnaev interfered with their representation of him.

O’Toole called on lawyers and prosecutors to resolve their differences, saying that the tight restrictions could be appropriate, but that there is a difference between them being “annoying” and them being “inhibiting.”

Federal prosecutors later agreed to ease some of the restrictions, by expanding the list of people from the defense team who could visit Tsarnaev on their own, and allowing them to talk to third parties about their conversations with him.

The defense lawyers argued in the court filing today that, since then, they have grown concerned with FBI monitoring. The lawyers did not specify what type of monitoring is occurring: Several arguments in the court documents related to the FBI have been redacted, apparently with the approval of the court.

The defense lawyers added, however, that the Bureau of Prisons has recently asked to screen digital records that the defense team has brought to the prison, even though the prison had earlier set up a computer for Tsarnaev and his lawyers to view materials without interference.

“Defense counsel declined to submit to the review and therefore were unable to review the material with the defendant,” the lawyers said.

The lawyers called for prosecutors to form a “taint team,” which could be made up of lawyers and law enforcement officials who are not related to the case, that could determine what documents could be subject to screening and which documents properly constitute defense materials. Otherwise, the lawyers argued, O’Toole should lift the restrictions.

Tsarnaev, 20, faces multiple charges that could bring him the death penalty, for allegedly setting off the April 15 bombings that killed three people and injured more than 260. He and his brother, Tamerlan, were also accused of shooting an MIT police officer. Tamerlan was killed during a confrontation with police in Watertown four days after the bombings.

Prosecutors announced last month that they would seek the death penalty for Tsarnaev. O’Toole set a trial date for November.