"There is a high threat from terrorism," a British travel advisory read. It warned Islamic militant group Boko Haram mounts attacks on northern Nigeria on a regular basis.
An advisory published Monday from the British Foreign and Commonwealth Office said to avoid Borno and four other northeastern Nigerian states because of the likelihood of violence.
The Punch, a Nigerian newspaper, reported Monday one soldier was among the 51 reported dead after Boko Haram launched attacks on Borno state during the weekend. The newspaper reported security officials were meeting behind closed door to assess the situation.
At least 100 people were killed during Boko Haram attacks in the region in the past week, the Nigerian report said.
The U.S. State Department in November designated Boko Haram as a foreign terrorist organization.
The department described Boko Haram as a militant group with ties to al-Qaida in the Islamic Maghreb, a North African branch of al-Qaida. The designation includes militant group Ansaru, which the department said was a splinter faction of Boko Haram.