A Russian cargo ship that turned back home while travelling to Syria was carrying three repaired helicopters as well as air defence systems, Russian Foreign Minister Sergei Lavrov was quoted as saying on Thursday by the Interfax news agency.

Britain said on Tuesday that the Alaed had apparently headed back toward Russia after a London-headquartered insurer withdrew coverage from the vessel, saying it had been told of allegations it was carrying weapons.

"The ship was carrying air defence systems, which can be (used) only for repelling foreign aggression and not against peaceful demonstrators ... and it was carrying three repaired helicopters," Lavrov told Ekho Mosvky radio, Interfax reported.

Western nations want Russia to stop delivering arms to Syria but there is no UN embargo on such supplies and Russian President Vladimir Putin said this month that Moscow sends no arms that could be used in a civil conflict.

"We were not in violation of anything and we will continue to meet our obligations, set by the (UN) Security Council," Lavrov told Ekho Moskvy.

He said the helicopters were repaired under a 2008 contract and had been shipped in dismantled form, Interfax reported.

"To say that the Russians were bringing helicopters that could be used against peaceful demonstrators is a rather slanted position aimed to whip up passions and put Russia in a bad light," Interfax quoted Lavrov as saying.