Iran says it welcomes a "constructive" dialogue with world powers over its nuclear program but is refusing to halt its nuclear activities.

Quoting an official government statement, the IRNA news agency reported Wednesday that Iran is preparing to present a modified package of proposals aimed at ending the standoff with the West over its disputed nuclear program. The agency didn't elaborate.

Last week, President Mahmoud Ahmadinejad said Iran was preparing a new package of proposals and was willing build a new relationship with the U.S.

The U.S., European countries and China have invited Iran to a new round of nuclear talks. The U.S. and some allies believe Iran is secretly trying to develop atomic weapons — an allegation Iran denies.