Arguing that "transparency and robust accountability are a strategic national security imperative," 29 activist groups have sent a letter to President Obama asking him to investigate the most senior officials in the Bush administration over their roles in sanctioning the use of torture against terrorist suspects abroad.

The activist groups, which include a number of progressive religious groups as well as After Downing Street, the Center for Constitutional Rights and Code Pink, also accused the president of violating international law by suppressing the release of photos depicting abuse of prisoners at military detention centers in Iraq and elsewhere.

"Your actions ... indicate a troubling willingness to sweep torture under the rug, rather than openly address our nation’s regrettable recent history," the letter (PDF) tells Obama.

On Monday, the US Supreme Court set aside an appeals court's ruling that the Obama administration must release the photos, citing a new law passed in October that gives the secretary of defense the right to exempt photos from freedom-of-information laws.

Though the Obama administration had initially agreed to follow a lower court's ruling and release the photos, it reversed itself earlier this year and in October the president signed a law that gave the secretary of defense the power to exempt the photos from freedom-of-information requests. Secretary Robert Gates invoked that law last month.

"Every branch of the US government -- the executive, the Congress, and now the Supreme Court -- has shockingly acted to sweep evidence of war crimes under the rug," BORDC executive director Shahid Buttar said in a statement. "Their collusion is a profound betrayal of our nation's historical legacy, a setback for international human rights, and a devastating defeat for democratic transparency in the face of official misconduct."

The BORDC letter tells the president, "The ongoing secrecy surrounding evidence of torture ... amounts to suppression of evidence. You yourself have affirmed that 'nobody’s above the law,' even while acting to keep the dark past from being brought to light by pursuing a policy of secrecy. The secrecy your administration maintains over torture evidence ... appears to reflect the worst conceivable reason not to enforce the law: deference to a political calculus."

The letter argued that the standard argument for keeping the photos secret -- that their release would fuel anger around the world and put Americans in harm's way -- is not correct, and, in fact, the opposite is true.

"To the contrary, enforcing international law will help heal breaches with allies—many of which have voiced concerns about detainee mistreatment—and encourage greater support for our national security efforts going forward," the letter states.

"Your administration’s decision to hide torture evidence unfortunately compounds past crimes and further erodes the rule of law," the letter concludes.

The ACLU, the organization suing the federal government for the release of the torture photos, has said it will continue the fight to have the photos released, despite its loss at the Supreme Court this week.