QUITO: Ecuador has received bids from six oil companies for seven little-explored oil blocs with potentially high reserves, but investment in the area may be less than had been expected, the energy minister said on Tuesday.

Most of the bids by the companies for the so-called Intracampos blocs include provisions for Ecuador to receive some 60 percent of production.

The blocs are estimated by the government to contain some 854 million barrels of oil. "I don't know if we'll reach the expectation we had for $1 billion in investment," energy minister Carlos Perez told journalists. "I estimate, and this is approximate, that we'll reach around $600 or $700 million."

One bloc received no offers, he said. Contracts are expected to be signed in May.

Bidders are Russia's state-controlled Zarubezhneft, Uruguay's Petrobell, Colombia's Gran Tierra, Colombian-Peruvian consortium Frontera Geopark , the United States' Flamingo Operating and Ecuador's Petrolamerec.