The firmer trend seen towards the end of last week has continued this morning as the situation in Libya looks like it is coming to a head while repair work gets underway at the damaged Fukushima Daiichi power plant in Japan.City traders predict the top share index could open around 70 points higher.British Gas owner Centrica is to expand its retail presence in the US with the purchase of New York-based energy retailer Gateway Energy Services for $90m in cash, including $13m of tax assets plus additional working capital.Mining giant Rio Tinto is extending the acceptance period for its A$3.9bn bid for Australian coal miner Riversdale by three days to 6 April. The UK miner now either owns or has received acceptances in respect of 34.94% of Riversdale shares, up from 33.04% last Friday.Distribution group Bunzl has announced two acquisitions on opposite sides of the world. The company is to acquire cleaning and hygiene products distributor Cannon Consumables and has handed over the cash for Omega Hospitality Suppliers, an Australian supplier of catering equipment and disposables to contract caterers, hotels and other food service customers.