LONDON - WASHINGTON on Sunday came under increasing pressure to investigate allegations in the leaked Iraq war documents published by WikiLeaks, which Britain's deputy premier called 'shocking'.

Governments and human rights organisations alike put the focus on answers to the allegations made against US, allied and Iraqi troops as the whistleblowing website released 400,000 classified US military documents.

The flood of material from 2004 to 2009 offers a grim snapshot of the conflict, especially of the abuse of Iraqi civilians by Iraqi security forces.

The heavily redacted logs appear to show that the US military turned a blind eye to evidence of torture and abuse of civilians by the Iraqi authorities.

WikiLeaks claim the documents reveal around 15,000 more civilian deaths than were previously known about.

British Deputy Prime Minister Nick Clegg called the allegations 'extremely serious' and said people would be wanting to hear 'what the answer is'. 'We can bemoan how these leaks occurred but I think the nature of the allegations made are extraordinarily serious. They are distressing to read about,' he told BBC television.

'I'm assuming the US administration will want to provide its own answer.

Anything that suggests that basic rules of war and conflict and of engagement have been broken, or that torture has in any way been condoned, are extremely serious and need to be looked at.

'People will want to hear what the answer is to what are very, very serious allegations of a nature which I think everybody will find quite shocking.' There was no immediate reaction from the Barack Obama administration to the calls for an investigation, and little eagerness among Republicans to delve into the low points of a war that came to define the administration of George W. Bush.

US under increasing pressure