Two Covington & Burling partners have registered to lobby for the Filipino media site Rappler and its chief executive, now on trial for alleged libel in a case that supporters contend is tied to her criticism of the country's President.

The Washington-based Covington lawyers, Peter Lichtenbaum and Kurt Wimmer, said in a lobbying registration they would "seek to build awareness and concern about the unfounded charges brought against Rappler and its CEO and executive editor Maria Ressa in the Philippines".

Wimmer is a longtime First Amendment lawyer and served as the U.S. head of Covington's data privacy and cybersecurity practice. Lichtenbaum, a former senior lawyer in the U.S. Commerce Department during the George W. Bush administration, focuses on national security and economic sanctions.

Wimmer and Lichtenbaum were not immediately reached for comment on Monday about their advocacy for Ressa and Rappler.

The Covington team also includes former Ambassador Daniel Feldman, who joined the firm in April as senior of counsel. The former Akin Gump Strauss Hauer & Feld partner was not on the new lobbying registration.

Covington is working with Amal Clooney and Caoilfhionn Gallagher QC, lawyers at the U.K. firm Doughty Street Chambers who are counsel to Ressa, the founder and executive editor of Rappler and a critic of President Rodrigo Duterte of the Philippines. Time magazine this year named Ressa, a former CNN correspondent in southeast Asia, one of the 100 most influential people in the world.

Ressa's libel trial began in late July. Her backers argue she was arrested in retaliation for her reporting on Duterte.

"Maria Ressa is a courageous journalist who is being persecuted for reporting the news and standing up to human rights abuses," Clooney said in a statement in July. "We will pursue all available legal remedies to vindicate her rights and defend press freedom and the rule of law in the Philippines."

NPR reported in March that a spokesman for Duterte said Ressa's arrest "has nothing to do with freedom of expression or freedom of the press".

Rappler has no other federal lobbying contracts other than with Covington.

Covington is one of the top lobbying firms in Washington, according to a database maintained by the non-partisan Center for Responsive Politics. So far this year, Covington has reported nearly $8 million in revenue from federal lobbying.

Lichtenbaum has lobbied for Covington clients, including Amazon.com, Bombardier Inc., Kruger Inc., and BAE Systems Inc. Wimmer has lobbied for the Newspaper Association of America.