The administration's point man for South Asia, Assistant Secretary of State Richard Boucher, told rediff.com, "We are following (the situation in Sri Lanka [Images]) very, very closely because we are seriously concerned about the people who are trapped in the fighting and the people who are stuck in the safe zones."

"We have tried to work very hard with the government and the international NGOs (non-governmental organisations) to make sure that food and the medicines reach the people there. We think we've seen some progress there," Boucher said.

 "We are also very concerned that the Tamil Tigers have not permitted people to leave and are indeed putting people in harm's way. And, we have tried to make very clear they have to stop that," Boucher added.

He said that "we've also made clear that the government should not be shelling into the (safe) zones and that's something we've repeated several times and we will continue to press that point till be are absolutely sure there's no more shelling into the zone."

On March 13, US Secretary of State Hillary Clinton [Images] called Sri Lankan President Mahinda Rajapakse and expressed the United States' deep concern over the deteriorating conditions and the increasing loss of life in the government designated 'safe zone,' in northern Sri Lanka.

Clinton told Rajapakse that the Sri Lankan army should not fire into civilian areas of the conflict zone and called on him to give international humanitarian organisations and other NGOs full access to the conflict areas and displaced person camps so that Tamil civilians could be provided with food and medicines.

But when asked if the US was in consultation with India and were considering a joint operation reminiscent of how Washington and Delhi [Images] conducted joint operations in the wake of the tsunami a few years ago that devastated Sri Lanka, Boucher repeated that "It's hard to do an evacuation of civilians under fire."

"So, we need the parties to stop their fighting. We made very, very clear the Tamil Tigers should stop fighting and allow these people to leave and so that's what we are pressing very hard," he added.

Earlier, sources acknowledged that the plan was for US Air Force [Images] and US Navy units attached to its PACOM to go into the rebel-held hold-outs and evacuate these civilians faced with the prospect of fast-declining food and medicine stocks in these areas.

But the sources said that a US team that had gone out to these areas "to look at the possibilities for just this kind of thing (evacuation)," had concluded that "this is not likely in the current situation because that is not what the military calls a 'permissive' environment -- which means the two sides are not firing at each other and the two sides both agree to this."

"So, until there is that permissive environment," the sources said, it was highly unlikely "we'll see that kind of evacuation."

One source said, "In my view, this is not very likely," since even though the LTTE [Images] has been calling for a ceasefire, the Sri Lankan government has rejected this call, saying the only option left for the LTTE is for them to lay down their arms and surrender.

In February, a PACOM team was in Sri Lanka to discuss the possible contours of such a plan with the Sri Lankan military officials, during which the Deputy Chief of Mission in the US embassy in Colombo James Moore had been conducting an independent fact-finding mission in the island's northern areas formerly held by the LTTE. He had submitted a report about their dire situation and the declining levels of food and medicines and other provisions.

Consequently, sources said that there was interaction between the PACOM and the State Department about the viability of conducting a massive evacuation mission with a debate on the pros and cons of such a mission, but in the wake of the Sri Lankan government ruling out a ceasefire, the US administration had decided that in the absence of 'a permissive environment,' such a mission would pose grave risks.

Also, there was also the pressing problem of where, even if there was such an evacuation, these civilians could be taken to, and while there were the so-called safety zones set up by the Sri Lankan government, there was some consideration of Tamil Nadu in India, but was considered rife with political undertones of an Indian involvement, although sources said that such a mission would have certainly been done only with New Delhi's acquiescence and could have been a joint operation, considering that the US and India had worked together to bring relief to Sri Lanka in the wake of the tsunami that devastated the island nation a few years ago.

Sri Lanka has been peeved over New Delhi's call that it agrees to the LTTE's offer, if only to call a halt to the fighting to evacuate the civilians trapped in the areas where hostilities are occurring.