The World Health Organisation's study on links between mobile phone use and certain types of brain cancer has proved inconclusive.
The researchers said that even though there could be possible health risks from heavy mobile phone use, nothing conclusive has been found as yet.
"The study doesn't reveal an increased risk, but we can't conclude that there is no risk because there are enough findings that suggest a possible risk," the BBC quoted the study's chief author Elisabeth Cardis as saying.
The 10-year study of 13,000 people focused on both healthy users of mobile phones and those with two types of brain cancer -- glioma and miningioma tumours.
However, the study has been criticised as biased, because mobile phone companies provided 25 per cent of the funding.
The researchers claimed that problems with the study's methodology meant the finding was unreliable.
The heaviest phone users were reported to have a higher risk of both types of cancer but the researchers said 'biases and errors' in the study prevented them from making a causal link.
Some data also suggested that overall, mobile phone users had a lower risk of brain cancer than people who do not use one.
The director of the WHO's International Agency for Research on Cancer, which co-ordinated the study, said changing patterns of mobile phone use and lower emissions from handsets since the research began in 2000 meant further investigation into phones and brain cancer was needed.
Image: US President Barack Obama | Photograph: Kevin Lamarque/Reuters
