Last October, the Calgary-based company said it was selling its 25% stake in Greater Nile Petroleum Operating Co to a subsidiary of state-owned Indian oil company ONGC Videsh Ltd for $C1.2 billion.

At the time, Talisman said once the Sudanese government and other partners in the project gave their formal approval, and once rights of first refusal had been waived or had expired, the deal would be closed by 31 December. However, "complexities related to the consortium members' interest," resulted in the delay, the company said.

A company spokesman added that the end of Ramadan, a holy month for Muslims, in late November also slowed the approval process with the December holiday season for Christians also being an additional impediment.

Talisman's four-year foray into Sudan, which has been the site for a two decade long civil war, drew the ire of international human rights activists, who accused Talisman of generating revenue for a government that was engaging in human rights abuses against animists and Christians in the south of the country where rebel forces operate.