KABUL -- As cricism begins to mount over the pace of reconstruction in Afghanistan, United Nations Special Representative Lakhdar Brahimi has emphasized patience is needed after 23 years of conflict.

"Security remains the main concern of the Afghan people as well as the authorities but it is a problem that can only be resolved in the long-term or at best in the medium-term," said Brahimi who is in his second tour of duty as the UN's Special Envoy to Afghanistan. "One cannot hope for reconstruction in just a few months."

Brahimi warned last month at a meeting of the UN in New York that concerns over security in the north were particularly acute although a spate of incidents around the country have added to the general concerns, AFP reported.

"This security is the most serious issue, the main worry. It is not just the incidents themselves but the general atmosphere which leads to a feeling among Afghans that there is no real rule of law. "There has not really been any progress on this issue."

Brahimi has been a firm advocate of the deployment of troops from the International Security Assistance Force (ISAF) beyond Kabul.

President Hamid Karzai has seen his requests for such an expansion of the multinational force repeatedly rebuffed and Brahimi admitted that there had been "no progress" on the issue.

"The countries which are capable of implementing such an extension remain reluctant and say that they do not have the troops because of commitments in other countries," said Brahimi.

But Brahimi defended the level of support from the international community which had demonstrated a greater commitment to Afghanistan than to other troubled countries.

"The international community is very present, wants to help, more than in other situations. The level of interest and engagement by the international community is still satisfying and encouraging," said Brahimi. In response to criticism from some afghan ministers on the slowness of the disbursement of aid promised by foreign donors for reconstruction, Brahimi said that "the amount of money that has been handed over is clearly very, very much more than in similar situations."

Karzai has voiced his impatience over the release of funds for rebuilding the country's shattered road network and Finance Minister Ashraf Ghani has said that aid is being channelled more to meet humanitarian needs rather than reconstruction projects.

"Their impatience, which is totally understandable, is based more on unrealistic expectations rather than an objective analysis of what is possible," Brahimi added.

Karzai's government has been struggling to exert its influence beyond Kabul and revenue from customs duties has been slow to reach government coffers.

But Brahimi emphasized that "again the hopes are too big".

"The results have not met the levels of expectation, but there have still been considerable developments," he said, citing a weekend gathering of provincial governors in Kabul and the recent handover of customs duties from the western province of Herat.

Brahimi said that the long-term future of Afghanistan was largely dependent on the ability of the central government to extend its writ. "If you want Afghanistan to no longer be a country which produces terrorism, there must be a government in control of the country ... which can prevent its territory being used for terrorism."