WASHINGTON — No Americans’ telephones have been tapped without a court order since at least February, the top American intelligence official told Congress yesterday.

But the national intelligence director, Mike McConnell, could not say how many Americans’ phone conversations have been overheard because of American wiretaps on foreign phone lines. “I don’t have the exact number … considering there are billions of transactions every day,” Mr. McConnell told the House Judiciary Committee at a hearing on the law governing federal surveillance of phone calls and e-mails. Mr. McConnell said he could only speak authoritatively about the seven months since he became DNI.

In a newspaper interview last month, he said the government had tapped fewer than 100 Americans’ phones and e-mails under the Foreign Intelligence Surveillance Act, which requires warrants from a secret intelligence court. Mr. McConnell is seeking additional changes to the law, which Congress hastily modified just before going on vacation in August based in part on the intelligence chief’s warnings of a dire gap in American intelligence.

Under the new law, the government can eavesdrop, without a court order, on communications conducted by a person reasonably believed to be outside America, even if an American is on one end of the conversation — so long as that American is not the intended focus or target of the surveillance.