The building that houses EU summits, where toxic fumes forced EU leaders to switch venues last week, will be closed for a further week as investigators
seek to resolve the problem.
The fumes leaking from the drains have forced the Europa Building, also known as "The Egg," to be evacuated twice this month, including before a summit of EU leaders on Thursday and Friday.
The new building was opened in January amid controversy over its 321-million-euro ($378 million) price tag.
Staff and meetings will be temporarily transferred to the next door Justus Lipsius building until the issue is resolved.
About 20 catering staff had to go to hospital on October 13 and an unspecified number on Wednesday. An EU official said the Council and Belgian health and safety agencies believe the two incidents were due to the same source.
Reporting by Lily Cusack; editing by Philip Blenkinsop and Toby Chopra.