US President Barack Obama has welcomed the passing of his historic healthcare reform bill in the Senate, hailing it as the most important piece of social legislation since the 1930s.

The bill, which could lead to the broadest changes in the US healthcare system in decades, is aimed at providing healthcare to some 31 million Americans without insurance.

While Obama said the bill constituted "real and meaningful" reform, it must still undergo some tough negotiations with lawmakers from the House of Representatives, which passed a separate healthcare bill earlier this year.

The reconciliation process is likely to start in early 2010, although the bill may still be vulnerable to last-minute shifts of position and behind-the-scenes political deals.

Nevertheless, Obama said the Senate vote had taken America close to making health insurance reform a reality.

The bill passed in the Senate by 60 votes to 39, with Democrats voting with the president, and Republicans against.

Democratic Senate Majority Leader Harry Reid said the vote was a victory for the American people, while senior Republicans have vowed to put a stop to the bill's passage into law.

According to Republican Senator Mitch McConnell, the battle over healthcare reform is far from over.

The vote came after a Senate debate that lasted 24 days, following many months of political wrangling.

Analysts hailed the passage of the bill in the Senate as an extraordinary achievement for Obama, although critics have slammed it as too expensive, authoritarian and rushed.

The Obama administration has presided over a lengthy and complex drafting procedure, as the details of the proposed bill were finalised and presented for debate.

If the Senate's version of the healthcare reform plan carries the day next year, most Americans could end up with health insurance. One key provison is to ban private health insurers from refusing applicants with existing medical conditions.

Americans spent £1.36 trillion (US$2.2 trillion) on healthcare in 2007, taking up 16.2% of GDP, a proportion which is almost twice that normally spent by richer countries.

The non-partisan Congressional Budget Office has said that £83 billion (US$132 billion) could be pared froom the federal deficit over the next decade if the bill becomes law, although critics counter that the savings may never in fact be realised.

Millions of Americans are currently unable to afford health insurance, faced with skyrocketing costs.