Abuja - President Goodluck Jonathan has sent a message of condolences to the government and people of Ghana on the death of President John Atta-Mills.
Atta-Mills, who came to power in 2009, died on Tuesday in Accra, aged 68.
In a statement issued in Abuja on Tuesday by the special adviser to the president on Media and Publicity, Dr Reuben Abati, Jonathan condoled with the family of the late president.
Jonathan said he received the news of the sudden death of the president with "shock and immense sadness".
He said the late president did his best during his tenure to "carry forward the process of democratic consolidation" and socio-economic development in Ghana.
Jonathan assured the people of Ghana of the sympathy and solidarity of Nigerians as they mourn the late president.
He prayed God Almighty to grant the late president’s soul eternal rest and bless his successor with the fortitude and wisdom to keep Ghana firmly on the path of peace, stability and progress.
Jonathan expressed the hope that the excellent relations between Nigeria and Ghana during the late president’s tenure would continue to be strengthened under the new leadership in Ghana in the mutual interest of both countries.
In his comments, former President Olusegun Obasanjo, who is in Ghana for an engagement, described Atta-Mills death as a "shock to the people of Ghana and all of us who knew him".
"He has been a stabilising influence in his country and indeed West Africa," he said.
"With the permission of President Atta-Mills, I was invited to the University for Development Studies, Tamale," Obasanjo told the News Agency of Nigeria (NAN) via telephone.
"I was scheduled to pay a courtesy visit to him today and while waiting, I visited Vice President John Dramani Mahama.
"A couple of hours after leaving the vice president, we heard about the death of the president at the Military Hospital," Obasanjo said.
He said that after due consultation with the authorities of the institution, he had decided that "as a matter of honour to the memory of the late President Mills, the scheduled lecture series be postponed indefinitely".
"My heartfelt condolences to the people of Ghana, the vice president and the family of the late president."
The former Gov. of old Anambra in the Second Republic, Chief Jim Nwodobo and Prof. Pat Utomi, described Atta Mills death as a tragedy for Africa.
Nwobodo described the news of Mills death as "very saddening and a rude shock".
He told NAN in a telephone interview that "Mill's death was a big loss for Africa in general and ECOWAS in particular".
"The relations between Nigeria and Ghana were liberal under his presidency. The face-off between Nigeria and Ghana over business concerns of Nigerians in Ghana would have escalated if not for his kind of person.
"He was a good man and I hope his successor would continue to maintain the good relations he had with Nigeria," Nwobodo said.
Utomi, the 2011 presidential candidate of the Social Democratic Mega Party, said that Mills was a part of the voice of thinking in Africa.
"He was an intellectual able to work with reform minded soldiers for the sake of his country.
"Mills managed to showcase Ghana as a rising democracy which is post marked as one of the most stable democracies in the world.
"I am deeply saddened to hear of his passing. He will surely be missed," Utomi said.
The Save Nigeria Group (SNG) spokesman, Mr Yinka Odumakin, described his death as "very unfortunate".
"Mills was one of Africa's statesmen. Men like him are rare in African politics," Odumakin said.