Iran's Bank Mellat seeks to sue the British government for a sum of at least 500mln pounds ($820mln) in compensation for the loss of business caused by illegal sanctions on Tehran over its nuclear energy program, a lawyer for the bank said. It is the first time that an Iranian lawsuit over sanctions has reached the stage of claiming compensation, Sarosh Zaivala said on Friday, press tv reported. On June 19, 2013, Britain’s Supreme Court overturned a ruling against Bank Mellat over its alleged links to Tehran's nuclear energy program. The highest British court ruled that the UK government was wrong to have imposed sanctions on the Iranian bank in 2009, and that the Treasury directive was “irrational” and “disproportionate.” The European Union General Court decided in January to quash sanctions imposed against Bank Mellat in July 2010. Western countries have taken a wide range of steps against Iranian companies in recent years including freezing their assets, blocking trade and preventing them from doing business with western banks in an effort to hinder Iran’s nuclear energy progress. At the beginning of 2012, the US and the European Union imposed sanctions on Iran’s oil and financial sectors with the goal of preventing other countries from purchasing Iranian oil and conducting transactions with the Central Bank of Iran. The sanctions entered into force last summer. The US-engineered sanctions were imposed based on the accusation that Iran is pursuing non-civilian objectives in its nuclear energy program. Iran rejects the allegation, arguing that as a committed signatory to the Non-Proliferation Treaty (NPT) and a member of the International Atomic Energy Agency (IAEA), it has the right to use nuclear technology for peaceful purposes.