US investigators have traced $150m in bribes given to Nigerian officials to Swiss banks, Nigeria's justice minister has said. Michael Kase Aondoakaa said the money was part of $180m in bribes given by US construction company Halliburton to Nigerian officials. The Nigerian government says it has asked the US to release the names of officials who negotiated the bribes. Halliburton admitted paying the bribes to top officials between 1994 and 2004. We have discovered that $150 million of the bribe money is in Zurich. That is the first shocking discovery. The entire money is $180 million. $150 million is already trapped in Zurich," Mr Aondoakaa said. Halliburton and its engineering subsidiary Kellogg Brown Root negotiated bribes with "three successive holders of a top-level office in the executive branch of the government of Nigeria" during that time, according to the plea agreement the company made with the US Department of Justice. The Nigerian government has come under pressure from the media to follow up the findings of the US court and prosecute the Nigerian bribe-takers. Mr Aondoakaa said they had requested the court unseal the judgement and pass on the names of the officials. Albert "Jack" Stanley, the former chief executive of KBR who pleaded guilty to making the bribes in order to secure $6bn in contracts, is to be sentenced on 6 May. KBR has agreed to pay more than $402m in fines, of which Halliburton, as the former parent company, agreed to pay $302m.