The Chancellor told the BBC that if the UK leaves the European Union (EU)without a deal, then the bloc will control many of the levers - including what happens at the French port of Calais.
The EU has set the UK a deadline of October 31 to leave the bloc.
Asked if the UK can control Brexit, he told the BBC: "We can't because many of the levers are held by others - the EU 27 or private business. We can seek to persuade them but we can't control it.
"For example, we can make sure that goods flow inwards through the port of Dover without any friction but we can't control the outward flow into the port of Calais.
"The French can dial that up or dial it down, just the same as the Spanish for years have dialled up or dialled down the length of the queues at the border going into Gibraltar."
French officials have previously rejected suggestions they could resort to a "go-slow" policy at Calais if there is no Brexit deal insisting that closing the port would be "economic suicide".
Earlier this month, Hammond told MPs a no-deal Brexit could cost the Treasury up to 90 billion pounds and said it would be up to them to ensure that "doesn't happen".
Davis, who quit as Brexit secretary last year, told the BBC that the Treasury wanted to avoid talking about the prospect of leaving without a deal.
Conservative leadership front-runner Boris Johnson has pledged the UK will leave the EU on October 31 - with or without a deal.
His rival, Foreign Secretary Jeremy Hunt has said he can negotiate a new deal for the UK "by the end of September" - and that he "expects" the UK will leave the EU before Christmas.
Voting among the party's 160,000 or so members is under way, with a winner expected to be announced on July 23.
( With inputs from IANS )