Israel is doing "immense damage" to the Middle East peace process by continuing with illegal settlement building, Nick Clegg said today in another escalation of UK diplomatic pressure.

The Deputy Prime Minister, speaking after talks with Palestinian president Mahmoud Abbas, said the construction amounted to "an act of deliberate vandalism" that threatened the two-state solution.

"Once you've placed physical facts on the ground that make it impossible to deliver something that everyone has for years agreed is the ultimate destination... it is an act of deliberate vandalism to the basic premise on which negotiations have taken place for years and years and years," he told a press conference in London.

"And that is why we have expressed our concerns as a government."

Mr Abbas is in the UK as part of a tour of European countries and is also having talks with Prime Minister David Cameron and Foreign Secretary William Hague.

Israeli and Palestinian negotiators have been meeting in an effort, sponsored by Jordan's King Abdullah, to restart formal peace talks.

But Israel has failed to halt the construction of settlements in sensitive areas despite international pressure, including from the United Nations.

Speaking after the talks, Mr Clegg said there was "no stronger supporter of Israel than myself as a beacon of democracy in the region".

"But the continued existence of illegal settlements risks making facts on the ground such that a two-state solution becomes unviable.

"That, in turn, will do nothing to safeguard the security of Israel itself or of Israeli citizens. That is why I condemn the continued illegal settlement activity in the strongest possible terms."