LOS ANGELES — The lawyer representing a US soldier accused of killing 17 Afghan villagers condemned Friday what he called an "information blackout" blocking him from preparing his defense case.

Attorney John Henry Browne said his team had been prevented from interviewing witnesses and injured civilians in southern Afghanistan following the alleged massacre earlier this month.

"We were expecting a lot more cooperation. The prosecutors in this case promised us a lot of cooperation which we're just not getting," he told reporters in Seattle.

"We are facing an almost complete information blackout from the government, which is having a devastating effect on our ability to investigate the charges preferred against our client," he added in a statement.

His client Sergeant Robert Bales, 38, is said to have walked out of his base in the southern province of Kandahar in the early hours of March 11 and mounted a massacre in two nearby villages, with many of his victims women and children.

Browne met his client earlier this month at the Fort Leavenworth military base in Kansas, where Bales is detained charged with 17 counts of premeditated murder, as well as six counts of assault and attempted murder.

But his team has made little progress on the ground in Afghanistan. "When we tried to interview the injured civilians being treated at Kandahar Hospital, we were denied access and told to coordinate with the prosecution team," it said.

The next day, prosecutors interviewed the injured civilians, but Browne's office found out shortly afterward that "the civilians were all released from the hospital and there was no contact information for them.

"In addition, we are being denied access to the injured civilians medical records that are in the possession of the government which makes it even more impossible for us to try to locate and interview these crucial witnesses," it said.

"The prosecution is withholding the entire investigative file from the defense team while the potential witnesses scatter into unknown and potentially inaccessible areas in Afghanistan."

Browne, who said his team had also not been shown an alleged video of Bales, conceded that under military trial rules, they do not have the right to shared "discovery" information until 30 days before a so-called Article 32 preliminary hearing.

"In this case, they actually promised us that if we sent people to Afghanistan... they would cooperate, and make witnesses available for us. And they've obviously violated that promise," he said.

He also warned that the defense -- which will have access to the results of a "sanity review" of Bales expected in the next two months and not made officially available to prosecutors -- could withhold cooperation.

"If they want cooperation from us they better start cooperating more," he told reporters.

Browne said earlier this week that post-traumatic stress disorder will almost certainly be part of his defense, adding that prosecutors will have trouble proving their case against Bales.

The killings have further strained the already difficult relationship between Kabul and Washington, at an all-time low after the burning of Korans by Americans, a spate of deadly anti-US protests and an earlier video showing US Marines urinating on the corpses of Taliban militants.

Copyright © 2012 AFP. All rights reserved.

Photo of Robert Bales by United States Army photograph by Specialist Ryan Hallock (28th Public Affairs) [Public domain], via Wikimedia Commons