A senior Iranian lawmaker warned Russia that its delay in delivering an anti-aircraft missile defense system to Tehran could harm relations between the two countries, state television reported Sunday.

Russia signed a contract two years ago to sell the S-300 surface-to-air missiles to Iran but has not made any deliveries or given any explanation for the delay. The United States and Israel strongly oppose the deal because it would significantly boost Iran's air defense capabilities at a time of heightened tension over the country's nuclear program.