European Union has besieged more Iranian shipping companies as a move to tighten sanctions which have been imposed on the Islamic Republic.

EU’s foreign minister agreed on Monday to add more than 100 new entities to the list of the companies and people who are affected by EU sanctions.

United States on Tuesday also announced sanctions on Venezuela’s State Oil company and six other oil and shipping companies for trading with Iran and violating the US ban.

EU’s move reflects the lack of progress in nuclear talks with Tehran.

The Islamic Republic of Iran Shipping Lines (IRISL) has also faced sanctions from both the EU and the US, which have said that the shipping line was engaged in illegal activities.

Iran in general and IRISL and its affiliates in particular face a largely unified front, one that is systematically, if somewhat slowly, closing the loopholes and forcing it to expend scarce resources on ever increasingly complex evasive manoeuvres, said J. Peter Pham with U.S think tank the Atlantic Council.

At some point or another, Iran's shrinking pool of partners will conclude that the cost of doing business with it is too high, he added.

IRISL chairman Mohammad Hossein Dajmar told news site Jamejam Online last year that sanctions could not paralyze the shipping line... Our strategy is to deal with this issue. It means we won't let them to reach their goal, Dajmar had said.

The EU measures have also targeted over 30 IRISL holding companies based in Germany, Malta, Hong Kong and the Isle of Man in the UK. All the companies were listed at the same address in each location, the EU's Official Journal showed on Tuesday.

IRISL was originally designated by the U.S. Treasury in 2008 for alleged involvement in illicit arms shipments.

US and UN sanctions has encouraged IRISL to become more active than before and play an active role in the international scene, Ali Ezzati, IRISL's director of strategic planning and international affairs said on the company's website this month.

Tehran said that they need nuclear power to meet the growing domestic demand for electricity, but US and EU suspect that Iran might be trying to develop an atomic weapon.