The United Nations today announced plans to evacuate about 140 wives and children of U.N. officials working in Uganda amid conflictin reports about what was happening in its capital city of Kampala.

Some U.N. officials reported that Kampala was under siege by Tanzanian troops seeking the overthrow of Ugandan President Idi Amin, while others insisted all was peaceful.

But the U.N. representative in Nairobi, Robert W. Kitchen Jr., said he had reports of fighting in the streets of Kampala and of tanks with Tanzanian markings in the city centre.

Radio Uganda, monitored here, reported that Tanzanian and Ugandan rebel forces for the first time bombarded Kampala tonight from 10 miles out with long range artillery. Radio Uganda broadcast an appeal from Amin to friendly countries to come to Uganda's aid.

Radio Uganda also announced there was heavy fighting on the road between Kampala and Entebbe, and said anti-Amin forces are preparing to bomb the two cities.

Despite these reports, a top U.N. officials contacted by telephone in Kampala presented a different picture of the situation in the Ugandan capital.

"Life is normal. Kampala is definitely all right. The government is not about to fall," he state emphatically.

He added that the United Nations is "recommending that dependents move out gradually. There will be no mass evacuation. The experts will stay."

U.N. officials in Nairobi said those leaving will be driven out in a convoy to Kenya while about 250 employes will remain.

Asked to explain the discrepancies between his account and the one from Kitchen, he replied, "The Nairobi office is overly nervous." He said reports of armed conflicts in Kampala had not originated from his office.

"There is sporadic shooting far away," the U.N. official continued. "There is definitely fighting to the south."

But he added that he has seen no tanks in the center of the capital city and there are "no more Ugandan troops than usual. Every night there is shooting near the army barracks, but that is only a warning for people not to move around."

There is a 12-hour curfew each night in Kampala, and residents there must dim their lights during the period, the U.N. official said.

Except for having to stay home at night, he stressed that life continues as usual. "My wife spent the day shopping," he said."We got fresh milk and the vegetable market is full. Only potatoes are in short supply"

He added that he had just finished a backgammon game with friends in his garden.

Other calls to Kampala residents produced similar stories.

One person at the U.N. office did say there had been some shooting and some tanks in Kampala during the day. But he said the tanks were "definitely Ugandan, not Tanzanian."

Well-informed itelligence sources said there are no Tanzanian tanks in Kampala. According to these sources and Ugandan exiles, the invading forces are massed at Mpigi, a small town on hihg ground 20 miles south of Kampala and Entebbe. There are numerous reports that the anti-government forces have been sporadically shelling Entebbe with long range artillery placed at Mpigi.

Another contingent has several the road between Kampala and Fort Portal in western Uganda. Intelligence sources say this contingent is now about 35 miles outside the capital.

Tanzanian officials and exile sources refuse to reveal the size of the resistance forces, stating only that "they are increasing every day."

Intelligence sources say Admin has less than two battalions, or 2,000 soldiers, left out of his original 20,000 man army. They are reportedly supplemented by an estimated several thousand Libyan troops. Libyan President Muammar Qaddafi yesterday announced he would "fully" back Admin, apparently meaning he will send in even more troops and supplies.

According to highly placed anti-Admin sources here, the anti-government forces are recruiting troops from the captured areas of southern Uganda, where an estimated 3 million people live. According to one source, "the plan is that it won't be the Tanzanian army which will make the final assault on Kampala. It will be the new Ugandan Liberation Army which is now in the process of formation."

In addition, anti-government sources said they want ot have their new government established inside Uganda before Kampala falls. The newly formed and broadly representative Uganda National Liberation Front is planning to set up a provisional government, probably at Masaka, at some future date. Only after this happens, these sources indicate, will the military drive against Kampala be launched.

Front officials argue that exaggerated press reports about Admin's imminent downfall play into the Ugandan dictator's hands. They say that now, as in the past, Admin wants to give the appearance that he is in serious trouble so that he can miraculously reappear in a few days. They add that such reports also give the impression that the resistance forces have been driven back when their true location is revealed.