The anti-arms NGO Economists Allied for Arms Reduction (Ecaar) and its lawyers were on Thursday mulling over government's response to their court action to scrap the arms deal.

The group has ten working days to respond to opposing affidavits filed by the state late on Wednesday - a day after a March 5 deadline.

Ecaar's South Africa chairman, Terry Crawford-Browne, told Sapa he would issue a statement next week once they had considered the arguments.

He described as "bizarre" and "incredibly weak" the papers submitted by the Finance Minister Trevor Manuel's legal team.

The state has argued, among other things, that Ecaar did not have the legal standing to bring a case against the government, and that the original papers should have been filed in Pretoria and not the Cape High Court.

It also wants a number of documents - including the Joint Investigating Team's arms deal report, affordability studies and all documents on the deal held by Parliament - dismissed as not relevant.

Ecaar and Crawford-Browne filed the court action at the Cape High Court on November 21 last year, on behalf of "all poor South Africans".

The NGO wants the government's controversial arms deal declared null and void, and all related foreign loan agreements - that Ecaar estimates will cost the country R115-billion - set aside.

It claims the deal is "strategically, economically and financially irrational, and thus constitutionally unlawful".

President Thabo Mbeki and Manuel were listed as the first and second respondents.

The lawsuit was filed shortly after Auditor-General Shauket Fakie, Public Protector Selby Baqwa and National Director of Public Prosecutions Bulelani Ngcuka unveiled a report on their probe into allegations of irregularities surrounding the deal.

The investigation found no "improper or unlawful conduct" by the government, and no grounds to suggest its contracting position was flawed.

The deal was originally priced at R30,3-billion, but according to Manuel in his Budget speech last month, this had increased to an estimated R52,7-billion due to the depreciation of the rand.

The Treasury was not immediately available for comment.