A Dubai-based Iranian businessman blacklisted in new US sanctions over Iran's ballistic missile programme said on Monday that he and his small company with just a single employee had been targeted by mistake.

Washington added 11 companies and individuals to a sanctions list on Sunday for supplying Iran's ballistic missile programme, in a move that was delayed by more than two weeks so as not to endanger this weekend's release of US prisoners.

The US, European Union and United Nations are lifting the broad financial sanctions that barred Iran from the global financial system for years, after a UN body certified on Saturday that Tehran was complying with an agreement to curb its nuclear programme.

The move amounts to the biggest return of a country to world commerce since the Cold War.

But Washington also maintains a separate, far more narrowly-focused list of companies and people who face sanctions over Iran's missile programme, unrelated to the nuclear sanctions.

The missile blacklist is not being lifted, and the new names are being added in response to the test-firing of a missile three months ago. Iran says it has not agreed to any limits on its missile programme, which is intended to carry conventional warheads not nuclear bombs, and the sanctions are illegal.

Keeping the missile sanctions in place is an important part of the US government's response to hardline critics at home and among allies in the Middle East, who accuse President Barack Obama's administration of making too many concessions to Tehran.

Those added to the US blacklist on Sunday include two Iranian businessmen based in Dubai: Hossein Pournaghshband and Rahim Reza Farghadani, and their respective companies, Mabrooka Trading Co and Candid General Trading.

The US Treasury said Mabrooka had supported an Iranian company in its efforts to acquire a production line for carbon fibre "probably suitable for use in ballistic missile components".

Candid was targeted for providing or attempting to provide "financial, material, technological, or other support to Mabrooka Trading and Pournaghshband". But Farghadani said his firm had been targeted by mistake because it shared an address with Mabrooka.

The two companies share a small office with half a dozen desks on the fourth floor of an eight-storey office block in Deira, a dilapidated commercial area on the northern bank of Dubai's creek in the UAE.

Hassan Khaja, an office assistant at Candid Trading, said he was its only other employee, apart from Farghadani. Mabrooka had two employees apart from Pournaghshband, he said. None were there.

Whatever the companies' role, their operations appear on their face to be a far cry from huge organisations like Iran's central bank and state oil and shipping firms, which are having global sanctions lifted as a result of the nuclear agreement.

Farghadani, a middle aged Iranian man dressed in an open shirt and jacket, told Reuters he could not understand why Candid had been sanctioned.

The two companies were entirely separate, he said, apart from sharing office space and a local sponsor, whom Khaja named as Ali Hashemi. In the UAE, companies operating outside free zones must be 51 per cent owned by an Emirati citizen.

Farghadani said Mabrooka had ceased operations and Pournaghshband left the country three months ago. He declined to comment further. The online registry of Dubai's Department of Economic Development showed no record of Mabrooka Trading Co.

Candid General Trading is registered. Its listed activities include trading of various goods including watches, computers and photographic equipment.

Iran on Monday said the new sanctions were illegitimate, vowing to continue developing its conventional military deterrent.-Reuters