London, April 19 (IANS): US President Barack Obama has signed a bill barring Iran's UN envoy-designate from entering the country, saying that he had engaged in "terrorist activities".

The bill that Obama signed into law Friday passed both houses of Congress over envoy-designate Hamid Aboutalebi's links to the students who seized the US embassy in Tehran in 1979 and held American diplomats hostage for 444 days, BBC reported.

"I share the Congress' concern that individuals who have engaged in such activity may use the cover of diplomacy to gain access to our nation," Obama said on signing the bill.

The US House of Representatives and the Senate had both voted requesting Obama to pass the bill.

Iran has lodged a formal complaint with the UN over the rejection.

Iran's deputy envoy at the UN, Hossein Dehghani, has asked Committee on Relations with the Host Country for a meeting over the decision, saying the the 1947 Headquarters Agreement where the US is generally required to grant visas to persons invited to the UN in New York.

"This decision of the US government has indeed negative implications for multilateral diplomacy and will create a dangerous precedence and affect adversely the work of intergovernmental organisations and activities of their member states," Dehghani was quoted as saying.

Aboutalebi, a senior political adviser to Iranian President Hassan Rouhani, has previously served as the Iranian ambassador to Italy, Belgium and Australia.

Aboutalebi has denied being a part of the group which laid siege to the US embassy and has insisted that he acted merely as a translator on a couple of occasions.

Starting in November 1979, 52 American diplomats and citizens were held for 444 days (Nov 4, 1979, to Jan 20, 1981) by radical Iranian students at the US embassy in Tehran following the overthrow of the pro-Western shah.

This incident has led to the severing of all diplomatic ties between the US and Iran for the past three decades.