German Chancellor German Schröder warned Iran on Tuesday against resuming sensitive nuclear activities, saying the West would not be divided in its opposition to Tehran building an atomic bomb. Schröder said the Iranian government could not pit European countries against each other over the issue and urged Iran not to make any "unilateral arrangements" during its ongoing negotiations with Germany and its EU partners Britain and France. The chancellor, who was accepting a peace prize from a German charity foundation, said the European Union was ready to offer major economic incentives if Tehran made significant efforts at resolving what he called a "difficult and highly sensitive" situation. But he warned that Iran would be making a mistake if it doubted the West's firm resolve to prevent Tehran from acquiring a nuclear weapon. Iran told the UN nuclear watchdog, the International Atomic Energy Agency, on Monday that it intended to resume uranium ore conversion, the precursor to enrichment in the nuclear fuel cycle. The move would violate a deal with the so-called EU-3 -- France, Britain and Germany -- under which Tehran agreed to suspend its nuclear activities in return for trade and security benefits. The United States, which also fears Iran wants to use its nuclear program to build atomic weapons, has backed the EU's diplomatic efforts.