A Ghanaian journalist who helped expose corruption in African football has been shot dead in Accra.

Ahmed Husein was part of a team led by award-winning journalist Anas Aremeyaw Anas, whose investigation led to the resignation of the head of the Ghana Football Association.

Dozens of football referees and officials in several countries were also banned as a result of the investigation, including the Nigerian national team coach, Salisu Yusuf, for receiving cash from undercover journalists posing as agents.

The director of the criminal investigations department, Maame Yaa Tiwaa Addo-Danquah, said: “Our men are on the ground currently gathering information. Everyone connected to this murder will be invited for questioning.”

Husein was shot in the neck and chest by unknown gunmen on his way home on Wednesday night in the capital Accra, police said. Anas tweeted: “Sad news, but we shall not be silenced. Rest in peace, Ahmed.”

Husein had previously made a complaint to police after a Ghanaian politician, Kennedy Agyapong, showed his photograph on a private television channel.

Agyapong promised payment for supporters who took retribution against Husein. “That boy that’s very dangerous, he lives here in Madina. If he comes here, beat him,” he said, pointing to Husein’s image.

Agyapong himself rejected claims that he “engineered the killing” of Husein, telling local radio station Neat FM: “He has never offended me. So, they should go and investigate those he has offended not me. He and his boss [Anas] have offended so many people in this country. The evil they have been doing will follow them.”

The Committee to Protect Journalists called for an immediate investigation and for Ghanaian authorities to “ensure that threats against the press are taken seriously”.

Ghana ranked 23rd out of 180 countries in the Reporters Sans Frontières (RSF) 2018 World Press Freedom Index – an improvement of three places on the previous year. RSF has previously condemned threats against Anas after he revealed “threatening calls, intimidatory messages and suspicious vehicles near his home”.

The reporter, whose other exposés have lifted the lid on graft in the judicial system, is distinctive for wearing hats and face coverings to conceal his identity.

Ghana’s national media regulator condemned the killing. “It will be in the national interest to arrest the perpetrators of this crime,” its chairman, Yaw Boadu-Ayeboafo, said in a statement.

Ghanaian journalists condemned the killing of the 34-year-old reporter, who played a key role in last year’s investigation.

Last October, Fifa banned the former Ghana FA boss, Kwesi Nyantakyi, for life and fined him nearly $500,000 (£387,000) after he was seen on camera allegedly accepting bribes.

Nyantakyi was accused of requesting $11m to secure government contracts. Eight referees and assistant referees were also banned for life and 53 officials were subject to 10-year bans. Fourteen officials were exonerated.

The revelations rocked Ghana, a country where football is the national sport and which prides itself on being a stable democracy in an often turbulent region.