KABUL: Officials from more than 30 nations and 40 international organisations gathered in the Afghan capital Thursday for a regional economic conference to explore ways of rebuilding the country after more than 40 years of war.

They met against a backdrop of tightened security, with road closures, blast walls and checkpoints illustrating the country's lingering instability despite a 14-year the North Atlantic Treaty Organization (Nato) intervention and billions of dollars in foreign aid.

Deputy Foreign Minister Hekmat Khalil Karzai opened the two-day Regional Economic Cooperation Conference (RECCA), at which delegates were to discuss policy priorities, inter-regional trade, harmonization of customs and border routines, and market expansion.

It is the 6th RECCA conference and the first since President Ashraf Ghani assumed office a year ago pledging to end the war against the Taliban and reform the economy.

Economists have forecast 2.5 percent growth this year, after Afghanistan averaged 9 percent annually from 2003 to 2012, according to World Bank figures.

The draw down of international troops last year has vastly shrunk the war economy that had provided employment for thousands of Afghans. Unemployment is on the rise, pushing increasing numbers of Afghans into the arms of the insurgents.

Pakistani national security adviser Sartaj Aziz will attend the conference on Friday and meet with Afghan leaders. Tensions have flared in recent weeks, with Ghani accusing Islamabad of failing to act against extremists operating along the porous border.

Seven police officers were killed in Afghanistan's southern Helmand province late Wednesday.

The provincial governor's spokesman Omar Zawak said the policemen, who were manning a checkpoint, were shot dead after their food was poisoned.

Helmand, a long-time Taliban stronghold and the source of much of the country's opium production, has seen a spike in insurgent attacks. The Taliban seized the district of Musa Qala last week, and were only driven back by Afghan forces days later, after 24 US air strikes.

Amnesty International meanwhile called for an investigation into the public flogging of a man and a woman, allegedly for adultery, in a remote province this week.

The couple were "illegally" sentenced to 100 lashes by a court in Chagcharan, the capital of Ghor province, Amnesty said. Video of the pair being whipped while a crowd of men looked on was widely circulated on social media.

Amnesty said the punishment was "cruel, inhuman and degrading," and far from an isolated example. It called on the Afghan government to "do more to impose tighter supervision of all courts, formal and informal, and also abolish corporal punishment entirely."