ZAGREB, Aug 20 (Reuter) - More than 20,000 Moslem refugees trapped along a Croatian road desperately need help that Croatia, trying to push them back into Bosnia, is preventing them from getting, the European Union said on Sunday.

"I call on the Croatian authorities to let humanitarian agencies and non-governmental agencies assist these people," Emma Bonino, the EU Commissioner for Humanitarian Affairs, said after visiting their makeshift camp she called "unbearable".

The refugees, followers of breakaway Moslem leader Fikret Abdic whose Velika Kladusa stronghold was overrun by Bosnian government troops, are Bosniàs least wanted people.

Croatia, overloaded with refugees, wants them to go home where Bosnian authorities say they will be safe. But the refugees, many of whom fought with rebel Serbs against Moslem-led government forces, fear reprisals if they return.

They have been stuck along a five km (three mile) stretch of wooded valley since they fled there almost two weeks ago. Some aid workers have got in to look after the sick and provide water and some food, but access has been very limited.

Torrential downpours as Bonino visited on Sunday have worsened conditions at the miserable camp, where people sleep under maize-stalk teepees, plastic sheeting or in cars.

"In the last days access has been made very difficult and for two days it has been forbidden," Bonino said. "The Croatian authorities assured me access (for aid) will be permitted.".

Croatian officials told her they intended to stick by an agreement signed a few days ago with Bosnia and with Fikret Abdic, who is under house arrest in Croatia, to persuade the refugees to turn back to their homes.

"We cannot accept -- and I do not think it is their (the Croats') intention -- that these people should be repatriated by force," she said. "I had a deep feeling that the people are not ready to go back, out of fear.".

Bonino, who travels to Belgrade on Monday to visit Serb refugees who fled Croatia when Croatian troops overran their rebel Krajina area two weeks ago, also saw Croats and Moslems being expelled from Serb-held Bosnia.

She said senior Croatian officials with her denied reports that Zagreb planned to stop accepting Moslem expellees along with Croats who fled from the Banja Luka area in tiny fishing boats across the Sava river to Davor in Croatia.

Some 11,000 people from the Banja Luka area have been expelled via Davor in just one week to accommodate Serb refugees from Croatia and to make the region ethnically "pure".

Ten percent of them were Moslems, Bonino said. Local Croatian authorities had said they were expecting many thousands more Moslems and Croats.

Croatia already copes with 400,000 refugees and displaced people -- almost 10 percent of its population.