Boris Johnson has underlined the Leave campaign's central claim that £350 million a week goes to Brussels, saying the figure is an "underestimate".
Mr Johnson said "about half" of the money comes back from the EU, but remains "under the control of EU bureaucrats".
"We don't control that money anymore and a huge quantity of it is simply wasted," he said.
The former London mayor also refuted claims that the key economic statement, which is painted on the side of Vote Leave's battle bus, is misleading.
Mr Johnson went on to insist that "European officialdom" is making "many decisions" on how the UK is run.
"For me that's only part of the problem, for me the real issue is the absence of control generally," he said.
"That manifests itself in all sorts of ways, lack of control of our borders, over our security."
Mr Johnson added that it is "wholly wrong" for a foreign court to make decisions on security that affect a sovereign country.