US oil firm ExxonMobil Tuesday expressed disappointment at the fact that it did not reach an agreement with the Venezuelan government on the nationalization of heavy-crude oil Orinoco belt.

ExxonMobil and ConocoPhillips, two of the world's major oil corporations, are leaving Venezuela following failure to attain a pact with Venezuela.

"ExxonMobil wants to express its disappointment that it did not complete an accord on terms for migration to a structure of joint venture. However, we continue to be engaged in talks with the Venezuelan government on the path to take," said Exxon in a communiqué, as quoted by Reuters.

Meanwhile, French Total, British Petroleum (BP), US Chevron and Norwegian Statoil initialed a memorandum of understanding with the Ministry of Energy and Petroleum to keep a stake -yet reduced-in Orinoco projects.