Britain should not begin the process of pulling out of the European Union until a new prime minister is in place, George Osborne has said.

In a message to nervous firms and investors, Mr Osborne stressed the economy was "fundamentally strong'' and "open for business" in his first public address since the UK voted to leave the EU.

Echoing calls by David Cameron, the Chancellor said in a speech that the triggering of article 50 – the formal process that would start Brexit – should be done by a new prime minister.

Mr Osborne added that he would address his future role in the Conservative Party "in the coming days''.

The Chancellor's call comes after Boris Johnson – currently the favourite to succeed David Cameron as prime minister, also said there was no "haste" in starting the irreversible process. In a column for the Daily Telegraph newspaper today Mr Johnson appeared to equivocate on what a Leave vote would actually mean. "There will continue to be free trade, and access to the single market," he wrote, adding that the secession process "will not come in any great rush".

All countries that currently have access to the European Single Market do so with full freedom of movement. Mr Johnson however said a points-based system would be put in place.

Despite the lethargic approach of British politicians, Brussels officials and other European leaders have called for Brexit to start as soon as possible and for a new prime minister to be put in place immediately.

Brexit reactions – in pictures Show all 10 1 /10 Brexit reactions – in pictures Brexit reactions – in pictures Supporters of the Stronger In campaign look at their phones after hearing results in the EU referendum at London's Royal Festival Hall AP Brexit reactions – in pictures Leave supporters cheer results at a Leave.eu party after polling stations closed in the Referendum on the European Union in London Reuters Brexit reactions – in pictures Mr Cameron announces his resignation to supporters Getty Brexit reactions – in pictures Donald Tusk proposes that the 27 remaining EU member states ‘start a wider reflection on the future of our union’ Getty Brexit reactions – in pictures Ukip leader Nigel Farage greets his supporters on College Green in Westminster, after Britain voted to leave the European Union PA Brexit reactions – in pictures Supporters of the Stronger In Campaign react as referendum results are announced today Getty Brexit reactions – in pictures Boris Johnson leaves his home today to discover a crowd of waiting journalists and police officers Getty Brexit reactions – in pictures Leave EU supporters celebrate as they watch the British EU Referendum results being televised at Millbank Tower in London Rex Brexit reactions – in pictures Supporters of the Stronger In Campaign react as results of the EU referendum are announced at the Royal Festival Hall Reuters Brexit reactions – in pictures Supporters of the Stronger In campaign react after hearing results in the EU referendum at London's Royal Festival Hall PA

Mr Cameron has however expressed a preference for his successor to be in place by the Conservative party conference in October. He stepped down on Friday morning following the Leave vote, which he campaigned against – but enabled by calling the EU referendum.

The Chancellor this morning also ruled out an emergency budget, despite pledging one in the event of Brexit as part of his EU referendum campaign.