Liberian President Ellen Johnson-Sirleaf has dismissed concern about corruption accusation from Leymah Gbowee, who shared the Nobel Peace Prize with her last year, saying she is "too young".
"My fellow Nobel laureate is too young to know what we've gone through to achieve peace and security in my country, to reach the level of democracy that we all are experiencing today," Mrs Johnson-Sirleaf, 74, said in London.
Mrs Johnson-Sirleaf, who became Africa's first female president in 2005, has been rebuilding a country devastated by civil wars from 1989 to 2003 that killed an estimated 250,000 people.
Ms Gbowee, a social worker, featured in Pray the Devil Back to Hell, a documentary about the Liberian women who took on warlords and the regime of Charles Taylor during the civil war.
Gbowee, 40, spoke in an interview with the BBC earlier this month, asking why the president's sons had important official jobs in the west-African nation.
"I have been through a process of really thinking, reflecting and saying to myself 'you are as bad as being an accomplice for things that are happening in the country if you don't speak up'," Ms Gbowee told the BBC in an interview.
Mrs Johnson-Sirleaf suspended her son Charles in August as a central bank deputy governor for failing to declare his assets, the BBC reported. Her son Robert is chairman of the state-owned National Oil Company of Liberia.
The Liberian president said today that she still wants to work with Gbowee.
"She agreed to be a part of the reconciliation process. Subsequently she has decided that she does not want to be a part of it. We respect that decision," Mrs Johnson-Sirleaf told the Royal African Society in London. "I suspect that, as we move on, working with others, that she will change her mind and she will become a part of that process because the nation needs all of its people."
Liberia is making progress in tackling corruption by working on prevention and punishment of crimes, she said.
"We have made progress that is going to address corruption," Mrs Johnson-Sirleaf said. "Punishment, I would say, we have fallen short of. Our judicial system is just beginning to be reformed."
The president said she has removed or fired people whom she believed had a "lack of integrity", although she was limited in what she could do until the justice system functioned better.
"Until there is prosecution to send a strong message of deterrence, we know that we won't have the full effect," she said, speaking at the meeting at Simpson's-in-the-Strand.
Mrs Johnson-Sirleaf was speaking in London to promote investment in her country. ArcelorMittal, OAO Severstal and Chevron are among companies that have invested in mining, rubber and oil industries in Liberia. The World Bank says 56 per cent of Liberia's 4.1 million people live below the poverty line.
"I hope that I will leave Liberia on an irreversible course of peace and prosperity based upon the proper use of its natural resources," Mrs Johnson-Sirleaf said.