Banking company TD Banknorth Inc. said Wednesday its first-quarter earnings more than doubled as revenue increased 44 percent. Earnings increased to $76.2 million, or 36 cents per share, up from $34.1 million, or 18 cents per share, a year earlier. Revenue rose to $400.3 million from $278.4 million. Without one-time costs and other items, TD Banknorth said it would have earned 55 cents per share in the quarter, in line with the analyst consensus estimate, according to Thomson Financial. TD Banknorth’s bottom line was weighed down by merger and restructuring charges and other losses. “It was a challenging quarter given the competitive environment for loans and deposits,” Chief Executive William Ryan said in a statement. Net interest income was $282.4 million for the first quarter, a 12 percent increase over the same quarter of 2005. Total assets at March 31, were $40.9 billion, up 27 percent from $32.1 billion at Dec. 31, 2005, due to the acquisition of Hudson United Bancorp of Mahwah, N.J., which closed during the quarter. TD Banknorth, which is based in Portland, has nearly 600 branches in Maine, New Hampshire, Vermont, Connecticut, Massachusetts, New Jersey, New York and Pennsylvania.