(Reuters) - Russian President Vladimir Putin said on Saturday that an African initiative could be a basis for peace in Ukraine but that Ukrainian attacks made it hard to realise.

He was speaking at a press conference after meeting African leaders in St Petersburg on Friday and hearing their calls for Moscow to move ahead with their plan.

"There are provisions of this peace initiative that are being implemented," he said. "But there are things that are difficult or impossible to implement."

Reuters reported in June that African mediation in the conflict could begin with confidence-building measures followed by a cessation of hostilities agreement accompanied by negotiations between Russia and the West.

Putin said that one of the points in the initiative was a ceasefire. "But the Ukrainian army is on the offensive, they are attacking, they are implementing a large-scale strategic offensive operation... We cannot cease fire when we are under attack."

On the question of starting peace talks, he said, "We did not reject them... In order for this process to begin, there needs to be agreement on both sides."

Ukrainian President Volodymyr Zelenskiy has rejected the idea of a ceasefire now that would leave Russia in control of nearly a fifth of his country and give its forces time to regroup after 17 grinding months of war.

(Reporting by Reuters; Editing by Alistair Bell)