During and immediately after the West African country's bitter civil war, foreigners were brought into leading posts, including the head of the police force, prompting debates about sovereignty.
Nine years on from the end of hostilities, Mattsson's position at the helm of the national side is preoccupying public opinion and the local media.
The controversy began with a cabinet reshuffle at the end of last year. Among other moves President Ernest Bai Koroma created a new ministry of `Youths, Employment and Sports'.
An estimated 800,000 young Sierra Leoneans, out of a population of six million, lack proper employment and the new ministry formed part of a plan to create more opportunities for young people.
Appointed as minister was Paul Kamara, a journalist and football enthusiast, who has been involved in a long feud with the country's football association (SLFA) after making allegations of corruption.
Kamara has long-standing connections in Sweden, and used his contacts to secure Mattsson to prepare the Leone Stars for their African Cup of Nations qualifiers.
"He has coached the Swedish U21 national team, he has been a scout for the Swedish national team," Kamara told Reuters in an interview in Freetown. "You cannot compare such a coach to our own local coaches."
Mattsson's initial engagement was for one game against Niger, and was underwritten by the Scandinavian head of Leocem, a cement manufacturer in Sierra Leone.
'UNFOUNDED STORIES'
The SLFA cried foul at the move though, saying the appointment of a coach was their prerogative, not the ministry's, and that other administrative committees established by Kamara represented an attempt to bypass them.
"He's been pointing fingers, writing scathing, unfounded stories against the football association, even before he became a minister," Abdul Rahman Swaray, acting general secretary of the association, told Reuters.
Swaray, standing in for Alimu Bah who has been suspended because of a corruption investigation, said he did not dispute the appointment of a foreign coach in principle, but he objected to the way the process was undertaken.
"It was just like a fait accompli," he said.
Kamara told Reuters the SLFA had not served football well.
"All the money that FIFA gives them - last year they received over one million dollars - they do not spend on development," he said. "The FA says we are creating parallel institutions, because they don't want to be checked."
The football association concedes there have been problems, but maintains it is now trying to put its house in order.
"It's very much unfair to some of us who are trying to turn things around," said Swaray.
Counter accusations flew between the two sides after the Leone Stars lost their Cup of Nations qualifier against Niger in Niamey in March 3-1.
