The sale of the 14 per cent stake follows the resolution in January of a bitter, two-year dispute between 327 dockers and the company's management.
ABN Amro Rothschild, acting as adviser to the Treasury, said pounds 70m was raised through the sale of 12.4 million shares at 565p each, which represented the mid-price on offers for the shares. The sale was oversubscribed, the company said.
The Mersey dockers were locked out in November 1995 after they went on strike in sympathy with staff at a local firm of stevedores. Since coming to power in May, the Government has resisted calls by union leaders to use its stake to intervene on behalf of dockers.
The dockers became a cause celebre last year as football stars such as Liverpool's Robbie Fowler backed the locked-out workers. In January, Mersey Docks and Harbour spent more than pounds 9m settling the dispute, offering the dockers a lump sum worth pounds 28,000 each.
Trevor Furlong, the company's chief executive, said the dispute was now behind the company. He also pledged to boost an investment programme, spending pounds 25m on a deep water berth and cold storage in Sheerness, Kent, and pounds 10m on the Twelve Quays ferry terminal in Liverpool.
The company's profits climbed by 16.6 per cent to pounds 34.6m last year - even after a pounds 10m provision for settling the dispute. Cargo volumes rose at both of its ports, Liverpool and Medway.
The Government now stands to make pounds 70m - compared to less than pounds 60m last year. Shares in the company have risen from 490p to 573p within the last year, valuing the company at more than pounds 0.5bn.
Mersey Docks shares closed up 3p at 576.5p.