The European Union (EU) president Herman Van Rompuy and UN Secretary-General Ban Ki-moon on Monday pledged to cooperate closely on all regional and international issues including violence in Syrian, the nuclear issue in Iran and the recent rocket launching by the Democratic People's Republic of Korea (DPRK).

"The priority now must be to ensure a complete cessation of violence in Syria and to allow for full and unhindered access to humanitarian aid," Van Rompuy said following a meeting with Ban.

He said he believed the UN to be key in breaking the deadlock in Syria, adding that supported the resolution adopted by the UN Security Council authorizing the deployment of unarmed military observers.

The EU president said the 27-member bloc was deeply concerned with the nature of Iran's nuclear program, underlying a set of tough restrictive measures aimed to press Iran to return to the negotiating table.

He expressed optimism on "engaging Iran in a sustained process of serious dialogue on the nuclear issue," citing positive signs from the talks with the Iranian side led by the EU foreign policy chief Ashton in Istanbul.

In the mean time, European Commission chief Jose Manuel Barroso also expressed support to the efforts made by the UN and its special envoy Kofi Annan in restoring peace in Syria after a separate meeting with Ban.

He condemned the recent military coup in Guinea-Bissau, calling on all those involved, in particular the leadership of the armed forces, to immediately restore the constitutional order and the rule of law in the African country.

Ban, for his part, praised the productive meetings with Van Rompuy and Barroso, saying that the UN welcomed a strong, strategic and collaborative relationship with the European Union.

"Working together, we can be politically stronger, and use our respective resources more effectively," he said.

He thanked the EU for its political and financial backing in many of the UN conflict preventing and reducing endeavors, such as in Lebonon, Kosovo and the Democratic Republic of Congo.

Ban said he discussed a wide range of issues, such as the situations in Syria, Afghanistan, Iran, Sudan and South Sudan, Mali, Guinea Bissau and the Democratic People's Republic of Korea, with Van Rompuy and Barroso.

He said the EU and the UN were "on the same page" and they were mutually committed to all the regional issues and global challenges.