KAMENSK-SHAKHTINSKY, Russia — Hundreds of trucks in a Russian aid convoy waited Saturday near the Ukrainian border as complicated procedures dragged on for allowing them into eastern Ukraine to help civilians suffering amid fighting between Ukrainian forces and separatists.

The main holdup was a lack of security guarantees from all sides in the conflict, said the International Committee of the Red Cross, which would have responsibility for distributing the aid.

Ukrainian officials are concerned that the mission, including around 200 trucks, could be a guise for Russia to send in equipment for the rebels, whom Kiev and Western countries claim are backed by Moscow. But Russia and Ukraine reached an agreement under which the trucks could enter with Red Cross accompaniment if Ukrainian border guards and customs agents approve the cargo.

Pascal Cuttat, head of the ICRC delegation for Russia, said agreement on how the cargo would be inspected and cleared was reached Saturday during several hours of talks between Russian and Ukrainian customs and border service officials.

“The challenge is we absolutely need security guarantees from all parties concerned before we can start moving,” Cuttat told reporters, adding that it was unclear how long this could take. He said they were also waiting for a reply from the Ukrainian government to a formal request for the cargo to be processed.

The Ukrainian officials met with their Russian counterparts in the Russian border town of Donetsk, some 125 miles east of the Ukrainian city with the same name. Cuttat said the cargo inspection would take place there. The trucks have been parked since Thursday in the town of Kamensk-Shakhtinsky, 17 miles from the border.

Fighting continued in eastern Ukraine, where three servicemen were killed in the past day.