Iran is pushing back against U.S. demands that it directly negotiate over its nuclear program or be bombed, warning neighbors that host U.S. bases that they could be in the firing line if involved, a senior Iranian official said.

Although Iran has rejected U.S. President Donald Trump's demand for direct talks, it wants to continue indirect negotiations through Oman, a longtime channel for messages between the rival states, said the official, who spoke on condition of anonymity.

"Indirect talks offer a chance to evaluate Washington's seriousness about a political solution with Iran," said the official.