Durban - The African National Congress in KwaZulu-Natal has opened a case of crimen injuria against Democratic Alliance deputy provincial leader Mergan Chetty for allegedly referring to foreign nationals as "amakwerekwere", the party said on Wednesday.ANC provincial spokesperson Mdumiseni Ntuli said charges of crimen injuria against Chetty had been opened at the Mountain Rise police station in Pietermaritzburg."The police at Mountain Rise have promised to investigate the matter."Ntuli said the charges emanated from a telephone conversation Chetty had with his former colleague, councillor Lungisani Sikhakhane, who was now an ANC member."In a recorded telephonic conversation, Chetty made derogatory comments, referring to foreign African nationals as amakwerekwere."Amakwerekwere is a derogatory term used to describe foreign nationals.READ: DA’s Chetty under fire over xenophobic slur'It was a joke'What concerned the ANC, Ntuli said, was that Chetty was not an ordinary South African citizen, but "an MP and deputy provincial leader of the second biggest party in Parliament".He said the ANC would continue to take action against South Africans who mad racial and discriminatory comments that offended other race groups."We were formed to deal with all issues of oppression, including race, geographic segregation, religious, gender and economic oppression. We will act against anyone advancing any of these in a manner that offends others."Chetty was not immediately available for comment.DA provincial leader Zwakele Mncwango said: "It can't be correct for anyone to use such derogatory terms, especially public figures, but we do understand that he, when he explains, said he was engaging [Sikhakhane] and they were joking about it."That is what [Chetty] said. [Sikhakhane] admitted to me that they were joking... I then asked him why he shared the conversation with his friends."'Suspicious timing'According to Sikhakhane, Mncwango said, he did not share the conversation to expose that Chetty had called foreign nationals amakwerekwere."If [Sikhakhane] is honest, he should tell the public what he told me, that it was a joke."Mncwango said he suspected that this was part of a political ploy."It is all about political grandstanding," he said."We live in a constitutional country and they [the ANC] have a right to take the matter up if they believe it was offensive. We will respect the rule of law. Let the police investigate the matter so that the truth can come out.However, he said, the timing was suspicious."The conversation took place four weeks ago and we have a by-election coming up as a result of one of our former councillors resigning in Ward 32 in Umsunduzi. It is clear what their intention is about."