Prime Minister David Cameron has written a heartfelt letter to the father of teenager Hannah Smith whose suicide was linked to the controversial website Ask.fm.

Mr Cameron sent the personal letter to David Smith after his 14-year-old daughter Hannah was found hanged two weeks ago, according to the Daily Mail online.

She had allegedly been bullied on the website but it has also been reported she sent herself the majority of the abusive messages.

In the letter the Prime Minister wrote about the pain he felt after his son Ivan, six, who suffered from cerebral palsy and epilepsy and died in 2009.

e wrote: 'I know from my own experience of losing a child that there will come a day when you see passt the pain to remember the happy times you shared together,' the Daily Mirror reported.

The Conservative leader insisted legislation exists to deal with online trolls, the newspaper reported.

Mr Cameron said he was grateful 'as a parent' to David Smith for highlighting the problem of bullying on social sites.

Mr Smith, 45, a trucker from Lutterworth, Leicestershire, had accused the Conservative Party leader of 'doing nothing' to stop youngsters falling victim to trolls.

The newspaper reported that Mr Cameron wrote: 'I want to reassure you that the Government takes this issue very seriously. There is already legislation in this area.

'Bullies mistakenly believe that because the abuse they inflict is happening online, it is beyond the reach of the law.

'I am very clear that it is not and the police should investigate it as they would any other crime.'

It was reported that the Government is giving teachers powers to search for and delete images and files on children's mobile phones.

Mr Cameron also reportedly told Mr Smith that MPs were 'working with industry' so parents can 'install internet filters for devices in the home'.

Mr Smith said: 'We need the law to change so sites can't operate if they don't have correct measures in place.'

Bosses at Ask.fm - set up for users to ask each other questions - have pledged previously to help Leicestershire Police over Hannah's death.

Mark and Ilja Terebin, bosses of the Latvia-based website, said it has the technology to identify 'almost all users' and that they are committed to supporting the investigation.

Specsavers, Vodafone, Laura Ashley, EDF Energy and charity Save the Children all pulled adverts from Ask.fm in the aftermath of the schoolgirl's death.

Mr Smith has asked friends and relatives of the tragic teenager to wear onesies to her funeral.

David Smith has banned traditional black from this Friday's service in favour of the all-in-one fashion garment in a bid to make the event a celebration of his beloved daughter's life.

According to The Sun, the 45-year-old said: 'I have asked all her friends to wear onesies because Hannah virtually lived in hers.

'I know she would be up there smiling if all her friends turned up at the church wearing their onesies.

'She would want us to be happy. No one is allowed to wear black. I want it to be a celebration of Hannah's life.'