ABUJA, Nigeria -- Nigerian security officials have thwarted plans by Boko Haram members to attack the embassies of the United States and Britain, authorities said Wednesday.

A Department of State Services statement said it broke up a ring that had “perfected plans to attack the UK and American embassies and other Western interests” in Nigeria’s capital, Abuja.

The statement said five suspects who had been based in Benue state and the Federal Capital Territory were arrested on March 25 and 26. Another 20-year-old Boko Haram member was arrested March 22 in Yobe state and “confessed his involvement in executing the sinister activities of the group.”

The statement gave no further details, and officials with the department could not immediately be reached.

Get Breaking News Delivered to Your Inbox

“For purposes of operational security, we do not comment on our security posture,” State Department spokesman Mark Toner said in Washington. He added: “The United States appreciates the work of Nigeria’s Department of State Security and Nigerian security forces in fighting terrorism and keeping citizens and residents safe.”

A British government statement also expressed gratitude for protection.

“We are grateful for the support we receive from the Nigerian security authorities in protecting UK diplomatic staff and premises in Nigeria,” the statement said. “We are in regular contact with the Nigerian security authorities concerning potential threats to UK interests in Nigeria.”

The U.S. State Department on April 5 issued an updated travel warning for Nigeria, warning that Boko Haram -- a group linked to the Islamic State of Iraq and Syria (ISIS) -- has targeted government installations and other venues in the past in the Federal Capital Territory and elsewhere. In 2011, Boko Haram attacked the U.N.’s Nigeria headquarters in Abuja with a car bomb that detonated in the reception area, killing at least 21 people.

“The Department of State warns U.S. citizens of the risks of travel to Nigeria and recommends that U.S. citizens avoid all but essential travel to Adamawa, Bauchi, Borno, Gombe, Kano, and Yobe states because the security situation in northeast Nigeria remains fluid and unpredictable,” the travel warning says.

Message for #AmCits: Nigeria Travel Warning: https://t.co/pUo8PpBPuL Security situation in northeast Nigeria remains fluid and unpredictable — U.S. Mission Nigeria (@USEmbassyAbuja) April 5, 2017

“U.S. citizens should be vigilant at public gatherings and locations frequented by foreigners,” it says. “Markets, hotels, restaurants, bars, and places of worship may become targets for terrorist attacks. Exercise extreme caution throughout the country due to the threat of indiscriminate violence.”

Nigeria’s president late last year declared the Boko Haram insurgency “crushed,” but its fighters continue to threaten the vast region around Lake Chad in defiance of a multinational force. It has increasingly used children, especially girls, as suicide bombers.

Boko Haram’s seven-year Islamic uprising has killed more than 20,000 people and driven 2.6 million from their homes, with millions facing starvation.

One faction of Boko Haram is allied with ISIS.