Home Secretary Theresa May Home Secretary Theresa May at a Downing Street reception to launch the helpline
Missing people and their families can now seek round-the-clock advice and support from the helpline provided by the charity Missing People.
Its website will provide the the latest appeals on missing children.
The initiatives are in response to the government's strategy on missing children and adults.
People can call the helpline on 116 000 when someone goes missing in any EU country.
The website, run by the charity Child Exploitation and Online Protection (CEOP) Centre with the help of Parents and Abducted Children Together (PACT) and Missing People, will also provide information for missing children or those who are thinking of running away and their families.
According to the UK's National Policing Improvement Agency, there were 327,000 incidences of missing people recorded by the police in 2010-2011.
Children and young people make up 66% of all those missing, it said.
'Role to play'
The helpline and the website have been launched to coincide with International Missing Children's Day.
Minister for Equalities and Criminal Information Lynne Featherstone said: "Missing children and their families are vulnerable, and International Missing Children's Day reminds us of the role we all have to play in protecting and supporting them."
She called on local and national organisations to "prevent, protect and provide support" for the missing children and their families.
A Home Office spokesperson said the government was providing funds to support the delivery of the special helpline for missing people and this financial year the amount stands at £220,000.
Martin Houghton-Brown, chief executive of Missing People, said: "Disappearances such as Madeleine McCann's tragically demonstrated the need for co-ordination across the world when a child goes missing; 116 000 is introduced so that people can call when someone disappears, regardless of which EU country they are in."
BBC news