COLOMBO, Nov 30 (Reuters) - Sri Lanka’s government and Tamil Tiger rebels have agreed to a temporary ceasefire to allow children in the war zones to be vaccinated against polio, military officials said on Thursday.

They said the United Nations children’s fund UNICEF had asked both sides to observe "days of tranquillity" on Friday and Saturday.

A similar truce was observed late last month, although each side accused the other of minor violations.

Ceasefires have been organised every year since 1995 when local aid groups launched their campaign to immunise children under five years of age against the disease.

A UNICEF statement said earlier that no cases of polio had been reported on the island since 1994, but children in the war zone were still at risk because "immunisation rates have been lower than average".

More than 61,000 people have been killed since the guerrillas began fighting for a separate state for minority Tamils in the country’s north and east in 1983.