Bermuda-based Brookfield Infrastructure Partners posted a big increase in fourth-quarter and full-year earnings due to a gain related to its merger with Prime Infrastructure in December.The company, which reports in US dollars, said it earned $416 million or $3.48 per unit in the three months ended December 31 compared with a loss of $45 million or 58 cents per unit in the same quarter during 2009.The large rise in net income was “primarily by the revaluation gain associated with the Prime merger”, the company said in results posted on its website, which showed it had recorded fair value gains of $433 million.On December 8, Brookfield Infrastructure completed its merger with Prime Infrastructure in a deal where just under 51 million limited partnership units were issued to former security holders of Prime Infrastructure. There now are approximately 157.4 million units outstanding, with Brookfield Asset Management Inc. owning about a 30 percent interest in Brookfield Infrastructure.For the full year, net earnings were $467 million or $4.25 per unit versus $25 million or 52 cents per unit in 2009.Brookfield Infrastructure declared an increase in its quarterly distribution to 31 cents per unit, up from 27 cents.