Expressing serious concern over the resurgence of Taliban in Afghanistan, a top United Nations peacekeeping official has said the militia have established de facto control over several border districts.

Because of deteriorating security situation, all UN missions have been suspended in Nimroz, Helmand, Uruzgan and Zabul provinces which, in turn, has greatly restricted the reconstruction process and the world body's ability to monitor the political process in the south, he said.

The primary sources of insecurity remained terrorist attacks and cross-border infiltration by suspected Taliban, Al Qaeda and Hizb-i-Islam insurgents, Under-Secretary General for Peacekeeping Jean-Marie Guehenno told the Security Council on Friday, days before a UNSC mission to the country.

As a result, he said all but one border district have been classified as 'high risk' by the October 15 United Nations Security Coordinator assessment.

Attacks by suspected terrorists against government, military and humanitarian workers are steadily increasing and they are predominantly targeting national, rather than international, personnel, he said.

Briefing the council on the security situation, Guehenno said the success of disarmament and electoral registration is dependent on improvement of security conditions.

Also see: Complete coverage of the war against terrorism