Nigeria’s tax authority asked lenders to freeze MultiChoice Group Ltd.’s local bank accounts to recover 1.8 trillion naira ($4.4 billion) in alleged tax arrears.

The decision came after South African-based MultiChoice refused to grant access to its servers for an audit, Nigeria’s Federal Inland Revenue Service said in a statement on Thursday. “MultiChoice Nigeria and MultiChoice Africa breached all agreements with tax authorities by refusing to communicate and blocking access to their records.”

The entertainment group, which has operations across Africa, has not received formal notification about the tax matter, MultiChoice said in a statement. “The matter is apparently based on unfounded allegations that MultiChoice Nigeria has not fully disclosed all existing subscribers to authorities. We have engaged openly with FIRS and the engagements are ongoing.”

MultiChoice fell as much as 5.9% in Johannesburg, reaching levels not seen since October.

It’s not the first time Nigerian authorities have tried to penalize a South African company over tax matters. The Nigerian unit of South Africa telecommunications giant MTN Group Ltd. faced a $2 billion tax claim from the nation’s Attorney General before it was dropped last year.