London, Nov 25 (IANS): British Prime Minister David Cameron said Sunday that the agreement reached on Iran's nuclear programme in Geneva was "an important first step".

"We now have an international agreement with Iran that moves it further away from getting a nuclear weapon," reported Xinhua citing Cameron. "This is an important first step, which must now be fully implemented."

After days of intensive negotiations, Iran and six world major countries, Britain, France, Russia, China, the US and Germany (P5 1), have reached a first-step agreement on Iran's nuclear programme, EU foreign policy chief Catherine Ashton announced Sunday morning.

"We will continue to enforce sanctions robustly in order to secure a comprehensive and final settlement that fully addresses the real and substantive concerns of the international community," Cameron said. "Today's deal with Iran demonstrates how persistent diplomacy and tough sanctions can together help us to advance our national interest," he added.

Meanwhile, British Foreign Secretary William Hague also welcomed the deal as an important moment in international relations with Iran and in efforts to prevent nuclear proliferation on microblogging site twitter.

Hague tweeted that the agreement with Iran was good for the whole world, including Middle Eastern countries and the people of Iran themselves.

"This agreement shows it is possible to work with Iran, and through diplomacy address intractable problems," the tweet said.

"Negotiations were painstaking. Tomorrow hard work begins of implementing and building on the agreement," he tweeted Sunday.