LONDON, Sept. 28 (Xinhua) -- Ed Miliband, the new leader of the Labor Party of Britain, unveiled on Tuesday his positions on deficit cuts, Iraqi war and vowed to change the party to regain public support.

In his first major speech after being elected, Miliband praised Labor's achievements, emphasizing the party "needs to change" after its election defeat in May.

Miliband paid tribute to his Labor predecessors but said the party had made mistakes under their leadership. "How did a party with such achievements to its name end up losing five million votes between 1997 and 2010?" he asked.

He attacked Prime Minister David Cameron for offering a "miserable, pessimistic view of what we can achieve, and you hide behind the deficit to justify it". "We won't let you get away with it", he told Labor Party members.

Explaining his views on diplomatic issues, he said while he supported the mission in Afghanistan, "I do believe we were wrong to take Britain into (Iraqi) war and we need to be honest about that."

The former energy secretary, 40, won Labor leader election on Saturday by just 1 percent over his elder brother, former Foreign Secretary David Miliband.