"The United States and their allies want to oblige Iran to suspend its uranium enrichment in an illegal manner," IRNA quoted Iran's ambassador to the International Atomic Energy Agency (IAEA) Ali Asghar Soltanieh as saying.
"But Iran will never submit to such an illegal act," he added.
IRNA said Soltanieh made his remarks in a speech late Tuesday to the School of Oriental and African Studies (SOAS) in London.
The comments are the latest indication that Tehran could reject the key demand of suspending uranium enrichment in a new package to end the standoff presented by world powers to Iran on Saturday.
The package