But Kiev again insisted it would not allow the convoy on its territory.
"No humanitarian convoy of Putin's will be allowed to cross the territory of the Kharkiv region," Ukraine's interior minister Arsen Avakov wrote on Facebook. "Provocation by the cynical aggressor will not be permitted on our territory."
Around 280 trucks are carrying more than 1,800 tonnes of "humanitarian supplies", including medical equipment, baby food, sleeping bags, and electric generators, according to Russian media.
But there are concerns by Kiev and the West that Moscow could use the operation as a cover for sending in troops.
More From This Section
Russian media said the shipment had passed through the city of Voronezh today, which would put it less than 300 kilometres from the border crossing at Shebekino, where the foreign ministry said the aid would enter Ukraine.
A Rossiya TV report from Voronezh said the convoy had over 500 kilometres to travel, and at an average speed of 60 kilometres an hour it would arrive at the border only in the evening.
Kiev has said the trucks would be stopped at the border for any aid to be unloaded and transported into conflict-torn eastern Ukraine with the help of the International Committee of the Red Cross.
Russian Foreign Minister Sergei Lavrov said yesterday that an agreement had been reached for the trucks to be inspected by Ukrainian authorities before continuing on with ICRC and Ukrainian representatives on board.
But Ukraine, which has accused Moscow of supplying the pro-Russian separatists with weapons, said no final agreement had been reached with the ICRC.