South African twins arrested over the weekend were planning attacks on the U.S. Embassy in the capital Pretoria as well as on buildings owned by Jews, police said on Monday.

Four South Africans, including the two brothers, faced charges related to terrorism in court on Monday, the spokesman for the elite police unit Hawks, Brig Hangwani Mulaudzi, said.

The four, who were arrested by authorities in Johannesburg on Sunday, will be detained in custody until July 19, when their case will be heard, Mulaudzi said.