Indonesia\'s state-run oil and gas firm PT Pertamina\'s president director Karen Agustiawan said on Thursday that his company may cancel the plan to purchase a 25- percent stake in the Area 31 oil and gas block in Angola, local media reported. She revealed that one of the current shareholders in the block had expressed its interest to acquire the stake, which was offered by US-based ExxonMobil. If that happened, she added, Pertamina would have to withdraw its offer. \"I only just heard that, but it\'s not yet official. I am still waiting for the official letter,\" she was quoted by the Jakarta Post.com as saying. As in many other countries in the world, Angola grants its current shareholders the priority to buy stakes offered by other shareholders. Pertamina has so far become the highest bidder for the 25- percent stake with the value of 3.5 billion U.S. dollars. The block is predicted to begin production in 2012.