Ugandan authorities have deported a Rwandan and a French national accusing them of undermining state security.
The two, identified as Annie Bilenge Tabura and Olivier Prentout, are employees of leading telecom provider MTN Uganda.
Ms Tabura is the general manager sales and distribution, while Mr Prentout is the chief marketing officer.
In a statement Tuesday, deputy police spokeswoman Polly Namaye said that security agencies in collaboration with immigration officers had been investigating the two foreigners "over their engagements in acts which compromise national security."
"We strongly believe that the deportation of the two foreigners, who were using their employment as tools to achieve their ill motives, has enabled us to disrupt their intended plans of compromising our national security," she added.
Rwanda has termed the deportation of Ms Tabura a "witch-hunt and harassment" of Rwandans in Uganda as tensions between the two countries continue to escalate.
"You should ask them [Ugandan authorities] why they keep doing this, not us," Mr Olivier Nduhungirehe, Rwanda's State Minister in charge of East African Community Affairs said, responding to the The EastAfrican.
"It is not the first time they have done this. This is a case of harassment of our nationals in Uganda."
Rwanda accuses Kampala of “arbitrary arrest and torture of Rwandans in Uganda" and for hosting rebels seeking to destabilise it. Uganda claims that Kigali is deploying spies in the country.
Mr Nduhungirehe said Kigali will "seek explanations" from Kampala, adding that there are also some Rwandans who were arrested in Uganda and "we don't know where they were taken."
“The Rwandan High Commission in Uganda always writes to seek clarification whenever such arrests are made but we never get responses. They never share evidence or give reasons why individuals are arrested. They kidnap, torture and then throw them out without a word,” Mr Nduhungirehe said.
MTN said in a statement Tuesday that Ms Tabura was arrested by unidentified security officers at their office in Kampala on Monday morning, while Mr Prentout had been arrested by police at Entebbe airport on Sunday, soon after he returned from a business trip.
The telco said the two "have been deported from Uganda to their home countries."
"MTN Uganda, together with all its employees, remains fully committed to operating within and respecting the laws of the country," the firm added.
The unit of MTN South Africa has had a run in with the authorities previously. In July last year, its data centre was raided by agents said to be from Uganda's domestic intelligence unit.
The firm said attempts to log into their servers were unsuccessful and that it reported to the police a case of illegal intrusion into the data centre and disconnection of four servers, but denied reports that it was being investigated over breach of national security and tax evasion.
MTN’s 20-year licence expired on October 20, 2018 but it was granted an interim licences, the second one which expired on January 20. The Cabinet had demanded a review of the telco's operations after it was accused of underdeclaring its call volume and therefore not paying its fair share to the taxman, a charge it denied.
Uganda maintains that arrests target individuals suspected of espionage.
While diplomatic ties between the two countries have remained strained, there are fears that the frostiness could affect cross-border trade.
Rwanda has since warned its citizens to "exercise caution while travelling to Uganda".
“This is a delicate situation that we need to deal with. We are in a Common Market and for now we are trying to talk to Uganda about these incidents,” Mr Nduhungirehe said.
Mayors of Rwandan border districts -- Burera, Nyagatare and Gicumbi -- told The EastAfrican that while the residents are aware of the tension, they are undeterred in their cross-border trade.
“Trade is normal, if not even better. We have not received reports of any harassment of Rwandan traders across the border,” Felix Ndayambaje, the Mayor of Gicumbi District told The EastAfrican.
“We, however, advise them to always avoid using porous borders, because if they use them and are arrested on the other side, we face limitations on helping them. We know of the tensions and that is why we warn the cross-border traders to be vigilant.”
The Rwanda Private Sector Federation (PSF) warns that if the two governments fail to deescalate the tension, it would change the business environment.
“I would want to see a better conducive environment between the two countries,” Robert Bapfakurera, the chairman of PSF said.
“Trade is still strong but anything which does not create a good environment affects business," he said, adding that business can only thrive if "the environment is without fear or any insecurity.”