Executives from some of Europe's biggest companies have warned that a vote for Britain to leave the European Union would reduce prosperity.

The U.K. goes to the polls on June 23 to decide whether it will remain part of the European Union.

More than 50 chairman and chief executives from companies, including ArcelorMittal (MT) - Get Report, L'Oreal (LRLCY) , Vodafone (VOD) - Get Report , Shell (RDS.A) and AkzoNobel (AKZOY) , wrote in a letter to the Financial Times that a decision to leave the EU would render both Europe and the U.K. weaker.

The group, known as the European Round Table of Industrialists, acknowledged that the EU needs to be improved and work has to be done in addressing challenges facing the union, especially terrorism and the refugee crisis.

"As leaders of some of the largest companies in Europe, we call for renewed confidence in the EU and as the first step in addressing our shared challenges," the group wrote. "Only a joint approach to common problems will achieve the changes needed to improve the living and working conditions of people of Europe, especially for young people and future generations."

However, the executives added that the scale provided by the EU gives "tremendous bargaining power in international trade negotiations, and the ability to defend our jobs and industries against external threats."

They also wrote that market liberalization in telecoms, airlines and energy has increased competition and efficiency.