The FMG placed an embargo on Biafra after Ojukwu declared the country an independent republic. However, this initial embargo did not include oil, only the shipping of other goods to and from Biafra. After the first embargo, Biafra began collecting oil royalties from companies operating within the country, and after Shell-BP agreed, the FMG then completed the embargo to include oil as well.
While the initial blockade, including the supplement inclusion of oil, was not extremely detrimental to Biafra at the time, it eventually led the starvation and death of thousands of people. Though estimates vary significantly, many people approximate that between 500,000 and two million people died due to starvation.
The ICRC’s role in Biafra was controversial, because it maintained its policy of not commenting on the war itself, and it did not run the blockade instituted by the FMG. Other organizations, just as Joint Church Aid, did defy the Nigerian government. Still, starting in 1968, the ICRC launched what was then its largest-ever delivery of food and medical aid.
see also:
Video: ICRC video on its Biafran relief work.
Article: Biafra: 1967-70: Ethical Dilemmas of Humanitarian Relief.