North Korea has had decades of self-imposed isolation
Percy Westerlund, speaking in Beijing after a three-day visit to North Korea, said the signing would probably take place in New York next month, a move he described as a positive signal.
Mr Westerlund, director general of the EU's external affairs division, said that North Korea should also "prove in deeds that they are actually prepared to join us in working against terrorism".
He said North Korea had also signalled it would sign up to other international conventions, but did not specify what they were.
Talks 'frank'
After the 11 September attacks on New York and Washington, North Korea issued a statement condemning terrorism.
But it has not backed the US-led strikes on Afghanistan, and has said the death of civilians "cannot be justified in any case".
The 10 hours of talks with the EU - described as "frank" - also included North Korea's relationship with South Korea and other issues.
The question of agreements on weapons proliferation was raised but "no
satisfactory answer was given", said Mr Westerlund.
And the response on issues of human rights and the treatment of Christians was "tentative and inconclusive", he added.
However, there had been "substantial improvements" in the regime's treatment of foreign non-governmental organisations (NGOs), Mr Westerlund said, adding that further improvements had been requested.
It was also announced that a high-level economic North Korean delegation would visit the EU in the first part of next year.
Dialogue disappointing
The EU is still waiting for North Korean leader Kim Jong-Il to make a visit to Seoul - a return trip promised after his landmark meeting with South Korean President Kim Dae-Jung in the North's capital Pyongyang in June of last year.
The EU established diplomatic relations with North Korea after the summit, when it appeared that the country was emerging from decades of self-imposed isolation.
EU delegate Patrick van Haute, Asia Director of the Belgian Foreign Ministry, expressed disappointment at the way the inter-Korean dialogue was going.
"We urge them to engage with South Korea and the United States," Mr Van Haute said.
Pyongyang recently forced a postponement of inter-Korean ministerial talks after it insisted on a different venue for reasons that remain unclear.
It also called off mutual visits of families divided since the 1950-53 Korean War, saying South Korea's anti-terrorism measures had made such visits unsafe.
"Our message is for them to talk and to stop finding reasons not to talk," Mr Haute said.
Future missions from the EU would depend on developments in Pyongyang's diplomacy, EU delegates said.
The US added North Korea to its list of state sponsors of terrorism after it refused to hand over four people who hijacked a Japanese airplane to North Korea in 1970.