The Obama administration is scrambling to assemble a package of harsher economic sanctions against Iran over its nuclear program that could include a cutoff of investments to the country’s oil-and-gas industry and restrictions on many more Iranian banks than those blacklisted, senior administration officials said Sunday.

The administration is also seeking to build a broader coalition of partners for sanctions so that it may still be able to act against Iran even if China and Russia were to veto harsher measures proposed in the United Nations Security Council.

“There are a variety of options still available,” Defense Secretary Robert M. Gates, speaking on CNN’s “State of the Union,” said of the potential list of targets for Iranian sanctions, notably in energy equipment and technology. He called it “a pretty rich list to pick from.”

Administration officials began describing what new sanctions might look like with a critical face-to-face meeting between the United States and Iran just four days away. The Americans are expected to press their demand for quick access and blueprints to a newly disclosed Iranian nuclear site.

American efforts to marshal worldwide pressure against Iran have gained traction since the revelation last Friday that Iran was operating a clandestine nuclear site.

Prime Minister Benjamin Netanyahu of Israel had earlier telephoned the House speaker Nancy Pelosion to urge the United States to pursue “crippling sanctions” against Iran, according to Israeli officials.

Secretary of State Hillary Rodham Clinton said on the CBS program “Face the Nation” that the administration was exploring how to “broaden and deepen sanctions.” Existing sanctions, she acknowledged, have been “leaky,” but the United States had learned from its experience with North Korea how to assemble a broad coalition behind punitive measures. “Sanctions out of the blue for punishment purposes, as much as I think they deserve it, probably don’t serve any useful purpose in resolving the issue,” said Thomas R. Pickering, a former under secretary of state who has held informal negotiations with the Iranians.

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