Former Olympic swimming champion Ian Thorpe ended months of rampant speculation and announced his return to the pool Wednesday, with an eye on making the Australian team to swim at next year's London Olympics.

The 28-year-old, nicknamed Thorpedo, quit competitive swimming in 2006 after a glittering career in which he captured nine Olympic medals, five gold, three silver and a bronze, at Sydney in 2000 and Athens in 2004 and 11 world championship titles.

It hasn't been something I've taken lightly, I made the decision last September, Thorpe told a televised news conference in Sydney.

I went to see the swimming venue for the London Olympics and it's an extraordinary venue and I could taste it, which is something I haven't felt for a very, very long time.

I didn't get back into the pool to get fit, I got back into it for (no) other reason to get back into the stage where I could compete at an elite level.

Thorpe registered for the drug-testing regime Wednesday. He must be registered in the program for nine months before he can compete.

Thorpe, whose speciality during the height of his career were the 200 and 400 meters freestyle, said he would target the relays and the 100 and 200 freestyle when he returned to competition.

It was on my bucket list to swim at another Olympics before I was 30, Thorpe added.

I've never not liked swimming. I like the laps, I like the training and the hard work and in the time out of the pool I have been able to get on with a normal life, but this is something that has just been nagging at the back of my mind.

I have set myself in preparing for London and it may continue after that.

The thing that is driving me, is being able to perform again.