Pakistan's Supreme Court is to investigate a scandal surrounding an unsigned memo seeking Washington's help to rein in the powerful Pakistani military, a decision announced on Friday that is bound to heap pressure on the weak civilian government.
The "memogate" scandal has highlighted historic tensions between the government and the military, in power for more than half Pakistan's 64 years and whose help Washington needs to battle militants fuelling violence in neighbouring Afghanistan.
Pakistan's politics were thrown into crisis on Oct 10 when businessman Mansoor Ijaz wrote in the Financial Times that a senior Pakistani diplomat had asked that a memo be delivered to the Pentagon with a plea for US help to stave off a feared military coup. This followed the raid that killed al Qaeda leader Osama bin Laden in Pakistan in May.
Ijaz, who is of Pakistani descent, later identified the diplomat as Pakistan's ambassador to Washington, Husain Haqqani, a close ally of President Asif Ali Zardari. Haqqani denied involvement but resigned over the controversy.
The decision puts additional pressure on the government. There is widespread speculation the probe could lead to Zardari's ouster if a link is established.
"I think that this is one of the darkest days in history for the judiciary," Haqqani's lawyer, Asma Jahangir, told reporters.
"I said in the Supreme Court too that this is a very disappointing judgment. This is a judgment that places national security above fundamental rights."
The court set up a judicial commission to investigate the scandal and present a report in four weeks.
It also directed the government to contact Research in Motion to obtain verification of Ijaz's claims of BlackBerry conversations with Haqqani.
The government has become increasingly unpopular since Zardari took office in 2008, failing to tackle myriad problems from crippling power cuts to suicide bombings and a struggling economy.
Speculation had swirled of an imminent coup, but all sides have since dismissed the rumours as baseless. Analysts say the military has plenty of other ways to pressure Zardari to step down.
Human Rights Watch said justice must be seen to be done in the investigation.
"In a sense, 'memogate' is a litmus test for all actors -- particularly the judiciary and the army," it said in a statement. "It remains to be seen whether the rule of law or the law of the jungle prevails in Pakistan."
Although his position is largely ceremonial, Zardari wields considerable influence as leader of the ruling party and his forced departure would be a humiliation for the civilian leadership and could throw the country into turmoil.