The group declared losses before tax of pounds 36.6m against profits of pounds 31m in 1991.
Sir Keith Stuart, chairman, said the property revaluations were intended to 'clear the decks, so we can move out into clear waters.
'They have been specifically commissioned so as to remove, as far as possible, uncertainty about our development portfolio.'
He added that pre-tax profits would have been pounds 47m without the property write-downs.
The revaluation, by Healy and Baker, was done 'more or less on a forced-sale basis', Sir Keith said, adding that there was no need for forced sales.
'Gearing is higher than we'd like, but there is loads of borrowing capacity left. The ratio of debt to equity rose from 55 per cent to 60 per cent. ABP has a further pounds 15m of off-balance-sheet debt.'
Sir Keith said that the ports business had been affected by a slowdown in the flow of higher- earning trades, such as timber. 'Given the depth and persistence of the recession, the ports business has produced a resilient performance.'
Profits in the ports and transport division were down from pounds 70.8m to pounds 64.7m. There was also a further pounds 4m of redundancy costs, following pounds 600,000 in the previous year.
Port-related property income was pounds 20.1m ( pounds 18.5m), while other property investment yielded pounds 9.1m ( pounds 7.9m).
Sir Keith said that the group had seen no clear signs of economic recovery. 'But there is some evidence that the fall in sterling is having some effect on exports.'
Despite losses per share of 14.3p, the total dividend rises to 8.5p (8p). ABP shares rose 2p to 403p.