The government is set to unveil plans to reclaim vast tracts of developed land along Spain's country's Mediterranean seaboard, and on the Canary and Balearic Islands that could leave thousands of British expats or second home-owners facing expropriation orders.

Environmentalists have welcomed the news, but fear that it may now be too late, that the five billion euros allocated to the scheme will prove woefully inadequate and that process may get bogged down in negotiations at a regional government and town council level.

The new legislation will primarily affect properties built within 100 metres of the coastline.

A spokesman for the British Foreign Office has told a journalist from The Times that Britain would "engage with the Spanish government and the regional authorities on any policy which had implications for British citizens who bought property in good faith."