The US state of California has approved the first phase of construction of a much anticipated yet controversial high-speed rail project linking Los Angeles and San Francisco, officials said.

Following years of contentious debate, state senators voted 21-16 Friday to allocate about $8 billion for the initial stretch of tracks for a line that is expected to see trains speeding along at up to 220 miles an hour (355 kph).

"The legislature took bold action today that gets Californians back to work and put California out in front once again," Governor Jerry Brown, a Democrat and longtime proponent, said after the vote on the eve of the summer recess.

All 15 Republicans voted against the funding measure, which comes at a time when California -- the most populous US state -- is struggling with budget woes that have forced it to cut services.

"Closing schools for three weeks while spending $8 billion on 130 miles of train tracks defies logic and is irresponsible," said Senate Republican leader Bob Huff.

The state's Assembly had approved the funding Thursday in a 51-27 vote.

The massive infrastructure proposal, initially approved by state voters in a 2008 referendum, has an estimated overall price tag of $68 billion.

Supporters say high-speed rail links in the state will reduce environmental damage, lessen the state's dependence on foreign oil, create hundreds of thousands of jobs and give a huge boost to California businesses.

Critics call the plan an overpriced white elephant that will never get completed. They say the system will be a huge financial drain on a state already struggling to pay its bills.

The approved funding allocates $5.8 billion for the first stretch of roughly 130 miles of tracks in the state's Central Valley, situated between Los Angeles and the state capital Sacramento.

That includes $2.6 billion in rail bonds and $3.2 billion in federal funds. In addition, lawmakers added $2 billion to improve existing tracks.

Construction is expected to begin at the end of the year or in early 2012, Lisa Marie Burcar, spokeswoman for the California High-Speed Rail Authority, told AFP.