Updated

The U.N. peacekeeping chief says some military units and officers who did not respond to a deadly attack on a U.N. base in South Sudan where 48,000 civilians had sought refuge will be sent home.

At least 25 people were killed in the February attack in the northern city of Malakal.

Herve Ladsous told reporters after briefing the Security Council behind closed doors Wednesday that he was not prepared to name the countries whose troops showed "a lack of responsiveness" because two U.N. reports on the incident are still being reviewed by lawyers.

He said that while some peacekeepers "reacted very well, some did not."

There was also a lack of understanding of the "rules of engagement" which spell out when soldiers can take military action, Ladsous said.