The Liberation Tigers of Tamil Eelam (LTTE) said they had no formal word from the government about its offer to send essential food and medicine to Jaffna through rebel-held territory.
"We have checked with the SLMM (Sri Lanka Monitoring Mission) and there is no official offer from the government except a statement to the media," LTTE military spokesman Rasiah Ilanthiriyan told AFP.
"We cannot react to this political gimmick aimed at the meeting of aid donors today in Washington," he said, referring to a review of Sri Lanka's faltering peace process by the US, European Union, Japan and Norway Monday.
The office of President Mahinda Rajapakse said on Sunday night that he had ordered the opening of the highway to Jaffna amid local and international concern for half a million civilians trapped there.
A government spokesman said a formal request was offered to relief agencies to support a food convoy by road to the Jaffna peninsula, virtually cut off since fighting erupted in mid-August.
"International humanitarian organisations are requested to offer their assistance to the supply of humanitarian goods to the Jaffna peninsula," said Chandrapala Liyanage, spokesman for President Mahinda Rajapakse.
The president's office announced Sunday night a large convoy of trucks would be assembled soon to transport essentials to Jaffna, where prices have rocketed with the closure of the only land access, via the A-9 highway.
Peace talks between the government and Tamil Tiger rebels collapsed in Geneva last month as the authorities resisted Tiger demands to open the A-9.
The severe shortages in Jaffna prompted neighbouring India to announce last week that it would send over 7,000 tonnes of food and medicine for the Tamil civilians in Jaffna, who are living under virtual siege conditions.
India's Foreign Secretary, Shiv Shankar Menon, was expected here this week to convey New Delhi's deep concern over the humanitarian crisis, diplomats said.
Minority Tamils in Jaffna share close cultural and religious links with the more than 60 million Tamils in India's southern state of Tamil Nadu.
The opening of the highway was a key element of the February 2002 truce brokered by Norway. New Delhi has backed Oslo's efforts to end the island's drawn out conflict which has claimed over 60,000 lives since 1972.

Copyright AFP (Agence France-Presse), 2006