The Conservative, who is chair of the Commons Foreign Affairs Committee, said: “The sharing of those messages is wrong. Not just because it’s embarrassing (it is that) but because it undermines the security of the British people.
“People around the world talk to our diplomats and officials because we’re seen as trustworthy.
“That means we’re often better informed than others and able to shape outcomes to our advantage.”
The former Army intelligence officer and military assistant to the Chief of Defence Staff added: “Trust matters in diplomacy just as it matters with the people we work with every day. If you trust someone you work better with them.”
He cites examples such as dissidents in Russia or a trade negotiator in Brussels, saying: “Now you learn that someone senior in the British government is leaking the most sensitive conversations and views about their closest ally – the US. Imagine how you feel then?
“Every conversation that doesn’t happen leaves British policymakers more likely to make bad decisions.
“Whoever did this has weakened the British government and harmed the interests of the British people. That’s why I’m so angry about it.”
Mr Tugendhat has called on the Metropolitan Police to investigate and bring charges against whoever was responsible.
