Greece's environment ministry says it has accepted a further offer from US energy giant Chevron to join hydrocarbon exploration efforts south of Crete.

"The Greek government has accepted the interest expressed" for the exploration areas south of Crete, the ministry said in a statement quoted by AFP.

In January, the ministry said Chevron was also interested in drilling for gas in the Ionian Sea, from the southwestern Peloponnese peninsula to western Crete.

The company wants to oversee exploration in an area of about 46,000 sq km, the ministry said.

US giant ExxonMobil has also expressed interest in an area of 35,655 square kilometres, it said.

A corresponding international tender is to be held, the ministry said.

In January, the environment ministry said Greece had increased the size of the area offered for hydrocarbon exploration by 25%.

It said it had doubled the proposed area by adding another 47,000 square kilometres, "thus significantly increasing the possibility of discovering natural gas reserves".

Environmental groups note that the areas earmarked for hydrocarbon exploration in the Ionian Sea are close to a planned marine park.

In January, the ministry said it would set aside additional space for the park, giving up the exploration of a small oil field near the port village of Katakolo and some other areas for gas exploration. I BGNES