Mohammed Sobeih, PLO representative to the Arab League, said at least 480 Palestinians were stranded in a no-man's-land near the Mediterranean sea, some without shelter, food or water.
"All our efforts to convince them to stop this tragedy were futile," Mr Sobeih said. Arab governments and UN agencies have also condemned the expulsions.
Most of the deportees arrived at the border camp within the last three days, after the Libyan government gathered them at the coastal town of Tobruk, about 70 miles west of the Egyptian border, Mr Sobeih said. Only 10 tents were set up at the camp, he said.
More are on their way to the frontier, but UN officials said they could not confirm the number. Mr Sobeih said 5,000 would be expelled this week, with 5,000 more next week.
Some 30,000 Palestinians lived in Libya before the expulsions began. Most are without documents that would allow them to enter other countries. Libya apparently hoped to embarrass the PLO by showing they have nowhere to go despite the signing of the Israel-PLO accord, which Libya opposes.
Earlier, UN officials said 1,500 Palestinians were stranded at Tobruk and suggested that hundreds more may be on their way to the border soon. Egypt stressed they would not be allowed to cross without travel documents.
A UN official said the Palestinians were given 48 hours to pack their bags before they were taken to Tobruk, and were ordered to sign documents saying they received all their salaries before they left. The UN High Commissioner for Refugees said it was planning to take supplies to the camp and would help Palestinians with valid travel papers enter Jordan or the Gaza Strip.