Some analysts say Nigeria’s massive fine of mobile phone company MTN Group risks damaging the country’s efforts to shake its image as a risky frontier market for international investors, Reuters reports.

Others say it shows Nigerian regulators want to enforce the law.

MTN must follow the rules in countries where it does business, South African Deputy President Cyril Ramaphosa said, according to a Naija247News report.

Shares in MTN traded 4.7 percent higher Wednesday after dropping about 20 percent since the fine was announced last week.

Nigeria accounted for almost 80 percent of South Africa’s trade in Africa in 2012. MTN Group’s alleged violation of Nigerian laws that resulted in a $5.2 billion fine could hurt trade relations, said a telecoms parliamentary committee head, Reuters reports.

“It is important for South Africa to increase trade relations with other African countries but if something like this happens we get worried about our reputation and the impact that would have on South African companies wishing to expand on the continent,” Mmamoloko Kubayi told Reuters.

Concerned that unregistered SIM cards were being used for criminal activity, Nigeria asked all telecom operators in August to verify the identity of their subscribers or face a fine of 200,000 naira ($1,005) per SIM card. The country is fighting an insurgency by Islamic militant group Boko Haram.

The Nigerian Communications Commission said in October all mobile phone companies had complied except MTN.

Africa’s largest mobile phone company was fined $1005 per SIM card by the Nigerian Communications Commission for failing in August and September to remove 5.1 million unregistered users from its network.

Nigeria is MTN’s No. 1 market, with 62.49 million subscribers as of September, according to the Nigerian Communications Commission. Johannesburg-based MTN is also the top mobile phone company in Nigeria by subscribers. The country’s No. 2 and No. 3 mobile service providers — Globacom and Airtel Nigeria — each have half as many subscribers as MTN.

The MTN fine follows a kidnapping on Sept. 21 of Olu Falae, former Nigerian finance minister, Reuters reports. Regulators say kidnappers used MTN phone lines to negotiate a ransom.

New Nigerian President Muhammadu Buhari has been promising tougher regulations.

Ramaphosa, a former MTN chairman, suggested MTN may be left to fend for itself without the support of South African authorities as it seeks to have the fine reduced, Naija247News reported.

“We will obviously be taking note of what is happening with a view of seeing how the company involved responds and reacts in this matter,” Ramaphosa told lawmakers in Cape Town Wednesday. “We would like our companies to comply with the laws and regulations of countries where they operate, without violating those.

“If this fine is indeed imposed as it is, it is going to impact on South Africa as well, as our revenue fortunes from a taxation point of view are going to be lower.”

The Nigerian Communications Commission gave MTN until Nov. 16 to pay the fine.

MTN said in a statement Wednesday no resolution has yet been reached with the Nigerian government, BizTechAfrica reported. “MTN continues to engage the authorities in Nigeria on this matter,” the company said.

Relations between Africa’s two largest economies soured further in April when Nigeria’s government ordered its two most senior diplomats in South Africa home following a attacks against immigrants including Nigerians in Johannesburg and Durban, Naija247News reported.

South Africa’s approach in this incident may be construed as weak and too cautious, said Nic Borain, a political analyst who advises BNP Paribas Cadiz Securities.

“South Africa does not have a track record of defending its national company champions internationally,” Borain said. “On the face of it, this fine seems seriously over the top. Ramaphosa’s words about the issue seem weak as they veer too much on the side of caution.”

MTN will be asked to explain why it was fined, said Nkhensani Kubayi, chairwoman of Parliament’s telecommunications committee. Hearings will also be held, most likely in 2016, to see if MTN is compliant with local rules.

“I believe the South African government should be doing more than … watching … what MTN does,” Athol Trollip, a lawmaker for the Democratic Alliance, opposition to the ANC. “They should give leadership on this.”

MTN said in a prepared statement it has operated in Nigeria for more than 10 years, and conducted its business in accordance with established principles related to sound corporate governance.

“Since launching more than a decade ago, we have made significant investments in connecting customers to our network. We take these responsibilities and obligations very seriously,” MTN said.

Other large South African companies investing in and doing business in Nigeria include Shoprite supermarkets and Standard Bank. South Africa’s oil imports account for the bulk of trade, according to Reuters.