Ukraine's state security chief Valentin Nalivaychenko on Friday said Moscow's decision to start sending the trucks across the border constituted a "direct invasion" and a "well-planned dangerous provocation," according to the Interfax Ukraine news agency. He added that Ukraine would not attack the convoy and wanted to avoid any confrontations.

Ukrainian military spokesman Andriy Lysenko told Reuters the convoy had violated agreements previously reached by Kyiv and Moscow, because the trucks "passed into Ukraine without clearance or participation of the International Red Cross or (Ukrainian) border guards."

Under the agreement, the convoy was to be accompanied by the International Committee of the Red Cross (ICRC), however the organization decided not to take part, citing security concerns.

"We are not part of the convoy in any way," Victoria Zotikova, a spokeswoman for the ICRC in Moscow, told the AFP news agency. "We have not received sufficient security guarantees from the fighting parties," she added.

Tired of 'delays'

The convoy of 260 trucks had been stuck at the border for around a week, as Ukrainian officials questioned the cargo on board, alleging that Moscow might be trying to supply pro-Russian separatists with weapons. Russia denies these allegations.

Earlier on Friday, the Russian Foreign Ministry released a statement saying its patience was wearing thin, and that its convoy of relief supplies - inlcuding water, food and medical supplies - had started moving towards the eastern Ukrainian city of Luhansk.

"Russia has decided to act," the ministry said, warning against any attempts to disrupt the convoy's movement. "We can no longer stand this outrage...all excuses to delay sending aid have been exhausted."

A humanitarian disaster has been unfolding in the conflict zone in eastern Ukraine in recent weeks. According to the United Nations, more than 415,000 people have been displaced since fighting between Ukrainian government forces and pro-Russian separatists began four months ago. More than 2,000 have been killed.

Russia's aid trucks are said to be en route to Luhansk, a rebel-held city, which has been without running water and power for more than a fortnight.

German Chancellor Angela Merkel is expected to meet with Ukrainian President Petro Poroshenko on Saturday.

nm/msh (AFP, AP, Reuters)