Tony Blair has urged Germany to do 'everything possible' to keep Britain in the European Union.
The former Prime Minister has been a prominent advocate to remain in the EU since and has now urged Merkel to try her best to reverse the decision made in the referendum.
He said: 'It would be a mistake of historic proportions if the United Kingdom leaves the European Union.
'Even Europe - especially Germany - has a lot to lose.
'It is in all our interests to maintain barrier-free trade across the continent and to hold liberal democracies together in times when authoritarian structures are resurgent.'
He added: 'Germany should do everything possible to keep the UK in the EU.
'The most important thing is to keep the door open if the British people decide to reverse their decision by voting on the outcome of the negotiations.'
The former Labour leader said Germany could play a key role in reversing the decision if it joined forces with France to push from reforms that may appeal to the UK.
Merkel said Germany has not changed its position on Britain leaving the EU, saying: 'We deplore it.'
She said that she now wanted to hear from the British on their proposals for a Brexit deal.
'We very much look forward to Britain again setting out its ideas,' she said.
Britain is due to leave officially leave the European Union on Friday March 29, 2019 - although a 21 month 'transition' deal where Britain will remain in the single market remain in place until 31 December, 2020.
The UK will be able to strike its own free trade deals in this period although they will not come into force until January 1, 2021.
