After months of negotiations and legal battles between Africa’s largest telecoms operator, South Africa’s MTN Group, and Nigerian authorities over a record $5.2 billion fine, there seemed to be progress with reports indicating that the two parties were about to settled for a reduced $1.5 billion penalty.

But the Nigerian parliament has thrown another spin to the whole debacle and is now asking that MTN pays double the amount it was originally fined to $10 billion, Bloomberg reported.

This will mean the MTN will have to pay $2,000 for each of the 5.2 million unregistered mobile phone lines it failed to register or deactivate before a September 2015 deadline, up from the original $1,000.

Abdulrazak Namdas, a lawmaker in the West African country’s House of Representatives, told Bloomberg that MTN had been dealing with the Nigeria’s attorney general instead of the Nigerian Communications Commission (NCC) in trying to get the fine reduced.

The NCC reduced the fine by a quarter to $3.9 billion in December before MTN withdrew a court challenge it had brought against the penalty and paid $250 million as a show of goodwill that it was committed to resolving the issue.

The Johannesburg-listed firm offered earlier in March to pay $1.5 billion to settle the dispute.

“For you to adjust the fine, you have to adjust the law, that is where I am finding difficulty,” said Yakubu Dogara, speaker of the House of Representatives, according to parliament’s minutes seen by Reuters.

The inquiry by Nigeria’s House of Representatives comes after lawmaker Ehiozuwa Agbonayinma asked, in a motion read out by Dogara, for the MTN fine to be more than tripled to $15.6 billion, IT Web reported.

MTN said in a statement it had noted reports out of Nigeria about the fine and would “await clarity and further guidance” on the fine from the federal government of Nigeria.

Shared in the telecoms operator fell more than 10 percent at the Johannesburg Stock Exchange on Tuesday after the reports emerged that the Nigerian parliament was probing the legality of the reduced hefty fine.