TEHRAN, May 17 (Xinhua) -- British Ambassador to Tehran Robert Macaire voiced his country's support for British companies working with the Islamic republic, local media reported Thursday.

"We are strongly committed to the JCPOA (Iran's international nuclear deal) and are seeking solutions to guarantee the agreement's benefits for Iran," Macaire was quoted by the PetroEnergy Information Network, which is affiliated to Iran's Petroleum Ministry, as saying.

Macaire made the remarks following the signing ceremony of a heads of agreement (HoA) between the National Iranian South Oil Company (NISOC) and a consortium of international companies, known as Pergas, for developing Iran's Karanj oilfield in the country's southwestern province of Khuzestan.

He said that there are differences between the European countries and the United States over their understandings of the JCPOA.

Macaire further said that Iran's market has massive potentials for private British firms and investors.

According to the PetroEnergy Information Network, an estimated investment of over 350 million U.S. dollars have been envisaged for developing the Karanj brownfield.

U.S. President Donald Trump declared last week that the United States would withdraw from the landmark Iran nuclear deal and would not extend the sanction waivers on Iran, claiming that the deal had failed to prevent Iran from developing nuclear weapons or supporting terrorism in the region.

However, European top diplomats on Tuesday agreed to follow through the 2015 nuclear deal despite Trump's decision to withdraw. They also expressed their support for the European investors in Iran.