Greenpeace has slammed Dell, HP and Lenovo after the three PC manufacturers went back on their promise to phase out toxic chemicals during production by 2009.

The companies had previously told the environmental group they would eliminate vinyl plastic (PVC) and brominated flame retardants (BFRs) from their products by the end of last year.

However, all three have said its unlikely they'll hit their targets. Lenovo has pushed the deadline back to 2010 but HP and Dell have yet to reveal a new deadline.

Greenpeace said that Apple was the only one of the world's five biggest computer makers to start reducing its use of toxic chemicals.

In its Guide to Greener Electronics , Greenpeace also revealed that Philips had considerably reduced its e-waste, putting the company 4th in the list of the greenest tech companies, compared to its position of 15th last year.

The report also praised Samsung for publicly supporting a reduction in greenhouses gases and Dell and HP for cutting in emissions in their own operations.