Chancellor George Osborne has said he wants the new regulator, the Financial Conduct Authority, to "look at the whole package" of charges for payday loans.
He said this would include considering a cap on arrangement fees and penalties as well as the interest rates, in order to put a "cap on the total cost of credit".
More top news
Police said the arrest showed how the matter was being taken "extremely seriously".
Windy with a soaking and limited winter sunshine
Mr Johnson said the checks would not be on goods travelling into Britain from the six counties.