EU flag. Photo: S. Solberg J.

The European Union has tightened sanctions on Iran’s financial institutions, trade, energy and shipping in a bid to persuade Iranian leaders to return to serious discuss over its nuclear program and avert possible military action.

The latest sanctions represent the most far-reaching to date by the 27-member bloc and come amid growing concern by EU leaders over the lack of progress over negotiations and Israeli military threats.

The new measures close many of the loopholes in existing EU sanctions and bring it closer to the U.S. restrictions, which had been more wide-ranging.

According to the Wall Street Journal, the EU prohibited all transactions between European and Iranian banks unless they relate to humanitarian aid and will blacklist additional entities in the oil and gas sectors.

“The EU’s message today is clear: Iran should not underestimate our resolve,” U.K. Foreign Secretary William Hague said in an e-mailed statement to Bloomberg.

“We will continue to do all we can to increase the peaceful pressure on Iran to change course and to return to talks ready to reach a negotiated solution by addressing the world’s concerns.”