A row has broken out in South Africa over an attempt to send weapons to deposed Haiti president Jean-Bertrand Aristide as rebels closed in on him.
Jean-Bertrand Aristide has now left his exile in the Central African Republic
President Thabo Mbeki has been accused by the leader of the opposition, Tony Leon, of violating the constitution by failing to tell parliament.
Mr Leon said an air force plane had been authorised to carry the supplies.
A spokesman for President Mbeki said it would investigate but denied breaking the constitution.
Mr Leon said that the constitution required President Mbeki to report any deployment of the South African Defence Force to parliament within seven days, but he had failed to do so.
The South African constitution contains clauses designed to prevent the government using covert forces across its borders -- a practice used extensively by the previous apartheid government, which left office 10 years ago.
Mr Leon told reporters in Johannesburg the plane had a shipment of 150 R-1 rifles, 5,000 bullets, 200 smoke grenades and 200 bullet-proof vests.
"It would now appear that President Mbeki approved the employment of a South African Air Force (SAAF) Boeing 707 to carry arms and equipment for the use of the Haitian Police Force in support of then-President Jean-Bertrand Aristide," said Mr Leon.
Mr Mbeki is expected to get another term in office after the April polls
He claimed Mr Mbeki authorised the aircraft's mission after making a personal commitment to support Mr Aristide to the Chairman of the Caribbean Community (Caricom), Jamaican Prime Minister P J Patterson.
Mr Leon said President Mbeki had contravened the constitution which required him to inform parliament before authorising the alleged mission.
He said Mr Patterson had confirmed that the SAAF Boeing 707 that left South Africa on 29 February 2004 had landed in Jamaica the same day.
The South African military plane however never reached Haiti because of the resignation and departure of Mr Aristide.
Mr Aristide has now flown out of exile in Central African Republic (CAR) to Jamaica.
South Africa faces general elections next month.