"The Movement for the Emancipation for the Niger Delta has stated that it will give 30 minutes notice to avoid civilian casualties," the British warning read. "You are advised to avoid busy areas and to exercise caution and observe vigilance at all times."
MEND is blamed for an Oct. 1 bombing in Abuja that coincided with the 50th anniversary of Nigeria's independence.
Nine people were arrested in connection to the blasts, including former MEND leader Henry Okah, who denied responsibility for the attack. Twelve people were killed in the bombing.
Authorities last week arrested Charles Okah, the younger brother of the former MEND leader, in connection to the Oct. 1 blast.
Henry Okah, under detention in South Africa, denied he had anything to do with the blast.
MEND has targeted Nigeria's petroleum sector in the past, claiming the government is not fairly distributing oil revenue.
Notable deaths of 2014 [PHOTOS]