British Prime Minister David Cameron said London’s financial district was under “constant attack” from European Union directives, the BBC reported yesterday.

During a flight from the EU leaders’ summit in Brussels to the Commonwealth Heads of Government Meeting in Perth, western Australia, Mr Cameron told a BBC reporter that Britain’s finance industry should be protected from EU measures.

“London – the centre of financial services in Europe – is under constant attack through Brussels directives,” Mr Cameron said.

“It’s an area of concern; it’s a key national interest that we need to defend.”

Mr Cameron’s comments came after Thursday’s Brussels summit, where leaders agreed to recapitalise banks across the EU, as part of a major deal to stop the debt crisis from engulfing the euro currency.

Mr Cameron’s statements coincided with reports that London Mayor Boris Johnson has written to José Manuel Barroso, European Commission president, to express his strong opposition to a proposed tax on financial transactions.

In the letter, Mr Cameron’s fellow Conservative asked for plans for the tax, known as the Tobin tax, to be abandoned immediately.

“At a time when many EU member states are struggling, some on their knees, it would be madness to weigh them down with this new mill stone,” the letter said.

Mr Johnson claimed the tax would limit European countries’ ability to compete with major financial centres such as New York and Hong Kong.

“Apart from weakening its financial sectors and London’s in particular, it will hamper the ability of businesses across Europe to compete in global markets and have serious implications for EU jobs.”

Mr Johnson called for energy to be directed towards designing sensible reforms to support financial sectors and promote growth of member states’ economies.