The French want to buy Britain's busiest cross-Channel port to safeguard their share of the ferry trade.
Dover Harbour is valued at pounds 150m, which would be paid by French taxpayers as Calais is state-owned.
Glenda Jackson MP, Opposition spokeswoman on Transport, said: "Last week, Michael Portillo was bragging about fighting them on the beaches - now his government is preparing to sell our beaches to the highest European bidder."
Dover Harbour Board has told Sir George Young, Secretary of State for Transport, that it is not opposed to privatisation, but wants a delay of at least two years so that the ferry companies can show they are able to compete against the Channel Tunnel.
Dover MP David Shaw is in favour of privatisation. His majority at the general election was only 836 votes, and Ms Jackson is to visit the constituency on Wednesday to open a campaign against the sell-off.
The DoT is expected to rule shortly on whether privatisation can be delayed. But in one of his last acts as Transport Secretary, Brian Mawhinney said the government was "minded" to push through the sell-off of Dover and two other ports resisting privatisation - Ipswich and Tyne Dock.Reuse content