UK-based explorer Tullow Oil said it has made new oil finds in Ghana and Uganda which are likely to lead to "material upgrades" to estimates of the amount of oil its fields hold.

Tullow said in a statement on Thursday that the Hyedua-2 appraisal well offshore Ghana and the Kingfisher-3 appraisal well in Uganda had both encountered oil.

The success of the wells has "substantially increased" the proven extent of its Jubilee and Kingfisher fields, the company said.