The Niger Delta Avengers and other groups have blown up oil pipelines throughout the year.
Kachikwu just got demoted but is still one of Nigeria's key figures.
Trade unions are angry about a 66 percent increase in fuel prices.
The West African country is experiencing a fuel shortage as militants attack pipelines.
The region's pipelines often need repair due to sabotage by militants.
People are waiting for hours to get gas in the West African country.
The NNPC previously denied it failed to submit funds to the public purse.