Shares in oil and gas company Cadogan Petroleum fell after said full year pre-tax losses widened as its Ukrainian assets were impaired by £63.5m.For the year ended 31 December 2009 loss before tax widened to £107.2m from a loss of £24.4m the year before. Revenue for the year increased to £2.3m from £1.8m previously, after good gas and oil sales from two of its producing wells.Cadogan said that as a consequence of the downgrading of the group's reserves and resources, its Ukrainian assets were impaired by £63.5m. Looking ahead the group said, "Despite the events that led to the change of management early in 2009, actions taken by the new management since then have greatly improved the company's position and outlook." Net cash and cash equivalents at year end fell to £30.5m compared to £72.0m in 2008.