BERLIN — Tensions between Germany and the United States over intelligence cooperation intensified on Wednesday, amid a domestic controversy swirling around Chancellor Angela Merkel and her allies over the scope and oversight of Germany’s role in European spying.

German politicians accused the United States of breaking a 2002 accord on sharing intelligence by pushing to expand its boundaries. Such moves, some said, jeopardize broader trans-Atlantic projects like a trade pact now under negotiation.

The agreement is a cornerstone of security arrangements put in place after the Sept. 11, 2001, terrorist attacks, which were plotted partly in Germany. But it is coming under strain after two weeks of controversy over whether the German foreign intelligence service, known as the B.N.D., spied on firms and individuals in Germany and Europe at the behest of the National Security Agency.

Interior Minister Thomas de Maizière, a close ally of Chancellor Angela Merkel and her chief of staff from 2005 to 2009, denied accusations from opposition politicians and some members of the news media that he and other members of the government broke German law by failing to supervise the intelligence agencies or ask tough questions about what the United States seeks from Germany.