Exiled Liberian leader, Charles Taylor, has filed a lawsuit against the Liberian justice minister over a search of his house in the capital, Monrovia.
The UN has voted to freeze Mr Taylor's assets
His lawyers say the search - aimed at finding items to help with Mr Taylor's prosecution by Sierra Leone's special war crimes tribunal - was illegal.
They have called for an end to the searches and any items to be returned.
On Friday the UN Security Council passed a unanimous resolution to freeze the former leader's assets.
The lawyers alleged that the war crimes court in Sierra Leone violated the territorial rights and sovereignty of Liberia in conducting the searches.
But Justice Minister Kabineh Janeh said they have an obligation to the United Nations to conduct the search as ordered by the war crimes court.
Mr Janeh told the BBC's Focus on Africa that they were prepared to defend their actions in court.
But Mr Taylor's lawyer said the Sierra Leone Special Court had no jurisdiction in Liberia.
"For us as Liberians to sit down here and only out of
fear allow our sovereignty to be infringed upon
when there is no treaty nor protocol between Liberia
and Sierra Leone... we think it is not correct," Mr Taylor's head lawyer, Richard Flomo, told the BBC's Jonathan Paye-Layleh.
Mr Taylor, who has been given safe haven in Nigeria, has been indicted for supporting rebels in neighbouring Sierra Leone.
Mr Flomo accused the prosecutors at the Sierra Leone court of drawing up Mr Taylor's indictment prematurely.
The war crimes court "has put the cart before the horse", he said.
"It means that in fact they didn't have any evidence on
hand before indicting Mr Taylor."