BRUSSELS—The European Union is imposing visa bans and asset freezes against three people associated with the government of Syrian President Bashar Assad. The measure brings to 128 the number of Assad's supporters targeted by the bloc.

Michael Mann, spokesman for EU foreign policy chief Catherine Ashton, said Monday that two Syrian entities were also added to the boycott list. This now includes 43 Syrian companies, banks, and other organizations.

The new measures, the 15th round of EU sanctions against Assad's regime and supporters, were adopted at a meeting of EU foreign ministers.

Continuing violence is undermining a U.N.-backed peace plan put forward by U.N.-Arab League envoy Kofi Annan, throwing into doubt the rest of the plan calling for talks between Assad's regime and those seeking to end his rule.