MADRID - Spain's lower house of parliament voted on Tuesday to start working on a bill that would legalise hundreds of thousands of undocumented migrants, based on a proposal by civil society groups that had collected more than 600,000 signatures backing it.

Political parties now have up to two months to amend the proposal and decide how to legalise the hundreds of thousands of irregular migrants living in Spain and make a final vote.

The #RegularizacionYa platform of around 900 rights groups and other non-governmental organisations behind the proposal estimates that the number of undocumented migrants in Spain could be close to half a million, around a third of them minors.

Migration researcher Jesus Fernandez Huerta said that recent changes to the law regulating permits and work visas for foreigners may have reduced this figure to below 300,000 people.

In a statement issued over the weekend, the Spanish Catholic Church called on political parties to support the legislative proposal. The conservative opposition People's Party backed the proposal after a last-minute change of heart.

The far-right, anti-immigration party Vox was the only one to vote against, with 310 votes out of 343 issued supporting the start of the legislative process.

The Socialist-led leftist ruling coalition had initially expressed doubts about the initiative, but ended up backing it, provided that it will be amended later.

Spain adopted a similar measure in 2005, when a previous Socialist administration granted an amnesty to around 800,000 people without documentation.

Spain registered 21 million legal workers in March, an all-time high with a large contingent of legal immigrants who often receive lower wages. Recent data compiled by the think-tank Funcas shows that the share of foreigners residing in Spain reached 18.1%, above the EU's average of 17.1%.

  - Reuters