Prosecutors and defense attorneys in the Boston Marathon terrorism case are quarreling over whether alleged bomber Dzhokhar Tsarnaev should remain in near-total jail lockdown before his trial begins this fall.

At the government's request, "special administrative measures" were placed on Tsarnaev that permit him little contact with the outside world, lest he try to communicate with Islamic extremists.

Prosecutors have said that while the FBI was monitoring phone calls between Tsarnaev and his mother, the mother twice mentioned that "close friends" of Tsarnaev's brother, Tamerlan, were with her in Dagestan. Prosecutors also have suggested that Tsarnaev's sisters, if allowed unfettered access to their brother, might send messages from him to outside extremists.

But defense lawyers maintain in court papers made public Monday that "there is no reason to believe" either of these scenarios.

They rebutted the notion that the sisters would "attempt to engage in terrorist tradecraft" while meeting with their brother.

Defense lawyers also complained that at one meeting with their client, an FBI agent monitoring the conversation was "needlessly intrusive and interfered."

They say the restrictions on Tsarnaev should be lifted because they are interfering with efforts to meet privately with him to plan a legal defense strategy and prepare for trial.

Tsarnaev, who potentially faces the death penalty, was arrested several days after the April 15, 2013, bombings that killed three people and injured more than 260 others when two pressure-cooker explosives detonated at the finish line of the annual marathon.

His older brother, Tamerlan, was killed in a shootout with police. Authorities say the pair committed the worst terrorist assault in this country since the Sept. 11, 2001, attacks.

The judge has yet to rule on Tsarnaev's lockdown.