Standard & Poor’s, the ratings agency, said in a statement on Monday that it was going to downgrade the infrastructure authority’s rating from CC to D. The clawback “was not done lightly, as it opens up the commonwealth to litigation,” it said. “However, we also believe it shows Puerto Rico’s reluctance to default on G.O. debt, where bondholders hold a particularly strong legal claim, and could represent a shot across the bow to bondholders in ongoing restructuring talks.”

S.&P. did not change ratings on other bonds but added that the lack of current audited financial information created “great uncertainty as to Puerto Rico’s true financial position.”

Executives of two bond insurers that had guaranteed some of the affected bonds wrote to Mr. García Padilla and his advisers last week, calling the clawback illegal.

“We are gravely concerned by this improper act, which violates numerous statutory and state and federal constitutional provisions,” said Nader Tavakoli, the executive chairman of Ambac Assurance Corporation, and Derek M. Donnelly, senior managing director of the Financial Guaranty Insurance Company.

Mr. Tavakoli and Mr. Donnelly argued that the clawback violated Puerto Rico’s law for the order of payment priorities, its constitution and several provisions of the United States Constitution.

But they said they were even more concerned about another diversion of money, which they said had begun in September, well before the governor invoked the clawback by executive order. They said as much as $94 million in federal excise tax on Puerto Rican rum, sold on the United States mainland, was supposed to have been placed in a trust fund, to pay principal and interest on bonds issued by the Puerto Rico Infrastructure Financing Authority.