MANILA, PHILIPPINES - Teenage Philippine singing sensation Charice Pempengco has caused an Internet uproar after having cosmetic surgery to improve her looks ahead of her debut on top US television show 'Glee'.

The 18-year-old, known simply by her first name, had botox injections and minor surgery in Manila at the weekend to narrow her rounded face, with the procedure filmed and broadcast afterwards on a national television station.

'It's one of the big preparations we are making for 'Glee' and of course I also want to look fresh on cam,' Charice said in a TV interview as she defended her decision to have cosmetic surgery at such a young age.

Fans, however, flooded the star's official website, www.charicemania.com, as the issue became a hot Internet topic, with many lamenting the fact that she felt pressure to alter her face.

'At a very early age, she was made to feel inadequate and was told time and time again that, although she had a killer voice, she did not possess the looks to make it as a 'star',' a fan using the name Marie wrote on Charice's website.

'I can't even begin to imagine what that did to this child's self-esteem.' On another fan site, www.charicemusic.com, there was more concern for Charice.

'I hope she doesn't change or undergo any more treatment and change herself... she's just fine as it is... listen to yourself and not be affected by other opinions,' wrote a user calling themselves Mirana on that site.

Charice's procedure was a top-10 global topic on the social networking site Twitter at one point this week.

Her plastic surgeon, Vicki Belo, said the procedure was meant to sculpt Charice's naturally rounded face.

Belo said the botulinum toxin injections, which immobilise some muscles, would not have any effect on Charice's voice.

The diminutive Filipina first gained global renown through video-sharing website YouTube and has since become a favourite of US TV talk show queen Oprah Winfrey.

'Glee' is an hour-long comedy series that follows an optimistic high school teacher as he works with a group of outcasts to revive the fortunes of the school's performance art club.