STOCKHOLM, Sweden (AP) _ Some Western nations are gathering food, medicine, coal and heating oil for the Soviet Union, but others are skeptical about Moscow's need for emergency aid.

They wonder if the Soviet Union, the world's largest grain producer, really needs food. They also worry about the Soviets' ability to distribute supplies.

Signals from the Soviet Union have been confusing, with some Soviets saying they have plenty of food.

President Bush said America would try to help if necessary. However, U.S. officials say there is no evidence of widespread hunger - that there is food in the cities and the agricultural regions of the Soviet Union.

Many relief workers and government officials hestitate to join the food effort because of reports that some parts of the Soviet Union refuse to share food with others. And in many cases, Soviets are malnourished or undernourished, not starving.

Officials at the Japanese Foreign Ministry, for instance, maintain help is more urgently needed by starving people in Asia and Africa. Japanese officials are considering sending medicine to the Soviets.

Germany, the biggest proponent of sending food to the Soviet Union, is worried about whether the goods will reach the hungriest people.

The German Red Cross says it has $2 billion to spend on shipping private donations, including hundreds of thousands of tons of sugar, milk, grain, heating oil, coal and toothpaste.

However, hundreds of trains carrying the Soviet Union's normal food purchases are halted at its borders because Soviet tracks are a different size and the foreign rail cars cannot enter the country. There are not enough people to unload the goods, so German food already shipped has not reached the interior.

''We know there are problems in the Soviet Union of things getting lost,'' said Mats Karlsson, who oversees Swedish aid to Eastern Europe and the Soviet Union.

He said many private organizations are reluctant to get involved.

''Our experience from other countries is that you are very dependent on the systems that exist,'' Karlsson said. ''(In the Soviet Union) ... the economic system is being changed, and we don't know what it's being changed to.''

Finland, the only European country with rail lines that match the Soviet Union's, sent railway officials to Germany this week to discuss the transportation problem. But the Finns say there is no need to send food.

''There is little on the shop shelves, but the people aren't starving, and there are no reports of hunger, either,'' said Pentti Partanen of the Finnish Red Cross.

The German branch of the Catholic relief organization, Caritas, said it would try to get past the Soviet rail bottleneck by setting up a truck convoy. Caritas is sending packages of staples to religious organizations around Moscow.

Germany, Italy, Canada, Spain and Britain have promised up to $10 billion in aid, Soviet President Mikhail Gorbachev's spokesman Vitaly Ignatenko said. Only Britain actually has set aside funds for the aid.

The Economic Community is also considering a $1 billion donation suggested by the Italian government.

Much of the food is being collected from individuals at Red Cross branches, and the Norwegian defense force and the Berlin municipal authority have offered their Cold War stockpiles of food. However, the International Committee of the Red Cross has no plans to discuss a coordinated relief project until early next month.

Sweden is concentrating on helping the Soviet Baltic republics establish free market economies. Britain has set up a $40 million fund to help the Soviets learn about food distribution, energy, small businesses and financial services.

Many other organizations and states say they are not considering sending aid because the Soviets haven't asked.

Soviet Ambassador Nikolai Uspensky said on Swedish television last week that the main problem facing the Soviets is ''the mechanism of bringing (the food) from the field to the shop floor, to the shop shelves,''

''When this chain breaks, there can be so many reasons: inefficiency, sheer sloppiness, it can be political motivations, sheer criminal motivations, anything,'' Uspensky said.

Halvard Kvamsdal, a former Red Cross official in Norway, said he often crosses the border to the Soviet Union and ''it has never been this bad.'' Still, when he asked his Soviet neighbors last week what they needed, they requested toys and clothes.

''Whoever has food is sitting on it,'' Karlsson said. ''There is a shortage, which gives rise to malnourishment. But the Soviet Union has been living with malnourishment for a long time.''