Harare, Zimbabwe - Zimbabwe's top lawyer may seek treason charges against former opposition politicians named in diplomatic cables released by WikiLeaks, a move that drew criticism Thursday from a prominent legal rights group.

Attorney-general Johannes Tomana said he has formed an unnamed five-member expert panel to assess some 3,000 Zimbabwe-related U.S. cables for breaches of security laws.

But Zimbabwe Lawyers for Human Rights chief Irene Petras said Thursday the constitution and terms of Tomana's official powers don't allow him to call in outside advisers. She called the investigation "an abuse of power."

Tomana says the panel cannot be identified for ethical reasons. He said he asked panel members to submit their legal opinions by March on contacts between U.S. diplomats and Prime Minister Morgan Tsvangirai's party that allegedly conspired to oust longtime ruler President Robert Mugabe.

Petras said Tomana's actions contradicted basic principles of openness and transparency in the judicial system.

"The attorney general is misconstruing his powers and mandate under the constitution," she said. "Can't he trust lawyers in his own office?"

Treason carries a possible death sentence in Zimbabwe. In 2007, Tsvangirai was acquitted on charges that he plotted the assassination of Mugabe, after a lengthy trial seen as a political ploy against the then opposition leader.

The WikiLeaks cables have included derogatory remarks about Zimbabwean political leaders on both sides of the coalition formed in 2009 after violence-marred and disputed elections in 2008.

The cables also referred to Western funding and diplomatic support for Tsvangirai's Movement for Democratic Change party and the need to undermine Mugabe's ZANU-PF party as well as to increase pressure on Mugabe's ruling elite through Western sanctions.

Mugabe has repeatedly branded as traitors former opposition leaders who backed the economic restrictions.

Relations between Zimbabwe and the West have been strained over a decade of political and economic turmoil that have fueled political violence and human rights abuses.

Tsvangirai's supporters accuse Tomana, a staunch Mugabe loyalist, of using parts of the WikiLeaks cables to discredit former opposition members ahead of fresh elections scheduled this year.

Petras on Thursday said the nation's police force and the attorney general's office "remain compromised and partisan in the discharge of their duties" in favor of Mugabe's party.

The two arms of the state did not act against perpetrators of violence in the 2008 elections, she said.

"Their failure to prosecute known perpetrators, their malicious persecution and prosecution of the innocent and their disregard for the rule of law bear primary responsibility with continued impunity and human rights violation in the country," she said.