The Movement for the Emancipation of the Niger Delta, MEND, has demanded the release of Henry and Charles Okah from detention as a condition for dialogue with the Nigerian government.
Henry Okah, a leader of the militant group, is serving a 24-year term in South Africa, in connection with the 2010 Independence Day bombing in Abuja that killed more than a dozen people.
His brother, Charles, is also facing trial over alleged involvement in the attack. He is currently under detention.
In a letter addressed to President Goodluck Jonathan, Friday, MEND also demanded the suspension of court proceedings, dropping of all charges, and presidential pardon to all its awaiting trial and convicted members.
"Our attention was drawn to your olive branch where you said 'Our doors remain open to them, (aggrieved armed groups) for dialogue and reconciliation if they renounce terrorism (armed struggle) and embrace peace.' As Theodore Roosevelt, the 26th President of the United States said 'Wars are, of course, as a rule to be avoided; but they are far better than certain kinds of peace,'" Jomo Gbomo, MEND's Spokesperson, said, referring to President Jonathan's Democracy Day speech on Thursday.
"The Movement for the Emancipation of the Niger Delta (MEND) has been disappointed in the past with Governments insincerity. Instead of addressing our concerns and dialogue on the root issues that led us to take up arms, your government, based on bad advisers, arrogantly jettisoned dialogue with our negotiation delegates, the Aaron Team in 2009, arrested and incarcerated perceived critiques.
"Since that slight, your government has known no peace from our region in spite of billions poured into propaganda and security. This slight was also responsible for the Independence Day attack of October 01, 2010, carried out to counter the impression that MEND has ceased to exist just because a few greedy, short sighted and misguided elements within and outside our ranks chose to betray their people.
"Unfortunately, avoidable lives which we regret were lost on that day due to the Security Agencies refusal to act on our advanced warning ahead of the attack," the group added.
While noting that it received the president's Democracy Day nationwide address with "cautious optimism," MEND stated that although it was a natural instinct to support one of their own, their agitation had never been about a Niger Delta President or 2015.
"We are looking at 2060, when our oil wells may have run dry and the future consequences to that generation yet unborn," Mr. Gbomo said.
"We hold you to your words, as the Movement for the Emancipation of the Niger Delta (MEND) declare a ceasefire effective 0700Hrs, Friday 30 May, 2014 by calling off our 'Hurricane Exodus' campaign and other acts of sabotage; especially our incessant attacks on gas and oil pipelines, erroneously or mischievously attributed to oil thieves," he added.
MEND further demanded that initial discussions with the government be facilitated through Kingsley Kuku, Chairman, Presidential Amnesty Programme, whom they will be comfortable to work with.
"Your response to us in the coming days and weeks may discourage or encourage other insurgent groups to follow suit, bringing about the real peace in our country that comes only after justice," the group added.