PARIS (AFP) - Two suicide attacks in Kabul, one targeting a play at a French-financed school, killed at least seven people on Thursday, the latest in a wave of violence assaulting the city as Nato forces pull out.

The Afghan capital has been hit by a series of deadly Taleban attacks in recent weeks, highlighting the fragility of the security situation as foreign combat troops leave after more than a decade of war.

The attacks targeted a bus carrying Afghan troops in the city's suburbs in the morning, and late in the afternoon a theatre performance at the Istiqlal High School, which is attached to Kabul's long-established French cultural centre.

"A suicide bomber blew himself up among the audience in Istiqlal High School," Afghan interior ministry spokesman Sediqi Sediqqi told AFP.

At least seven people were wounded in the attack, senior Kabul police official General Farid Afzail, told AFP, adding that the bomber is thought to have been a teenager.

Afzali and the interior ministry said one foreign national was killed, without giving further details.

But French Foreign Minister Laurent Fabius said the "barbaric" attack had left several people dead.

"I firmly condemn this terrorist act which caused the death of several people and left many injured. There were no French victims," Fabius said in a statement.

Witnesses described scenes of panic after the blast, with audience members screaming for help in the theatre hall, filled with smoke.

The cultural centre is located in the centre of Kabul, not far from the presidential palace and shares its grounds with the Istiqlal school, a French-financed institution that has taught generations of Afghan children.

Originally opened in 1970, the cultural centre was forced to close between 1983 and 2002 as Afghanistan was torn apart by a series of wars.

It reopened in 2003 and was revamped in 2010.

In the earlier attack, the bomber who was on foot targeted a bus carrying Afghan troops in Tangi Tarakhil on the outskirts of the capital, Afzail told AFP.

Taleban spokesman Zabihullah Mujahid claimed responsibility for the attack on the soldiers in a message sent to the media, but could not be reached after the school attack.

"As a result of the (first) attack, six Afghan army staff were martyred and 10 others were wounded," Afzail said.

A statement from the defence ministry confirmed the death toll, but said 11 people were wounded.

Kabul has been hit by a spate of deadly attacks in recent weeks, heightening concerns that Afghanistan could tip into a spiral of violence as the US-led military presence declines.

Nato's force in Afghanistan will change on Dec 31 from a combat mission to a support role, with troop numbers cut to about 12,500 - down from a peak of 130,000 in 2010.

Thursday's attack came as Washington announced it no longer holds any prisoners in Afghanistan, a day after a damning US Senate report on the brutal treatment of "war on terror" detainees.

In March 2013, Afghan forces took control from the US of the notorious Bagram prison, renamed Parwan, located on the sprawling US military airbase, but American forces had remained in charge of non-Afghan prisoners.

The running of Bagram jail, 40km north of Kabul, was highly controversial, with rights groups accusing the US of abusing prisoners. A US army report found that two inmates were beaten to death in 2002.

RISING VIOLENCE

The Senate report highlighted abuse at "black sites" around the world, several in Afghanistan including once known as the "Salt Pit" outside Bagram Air Base.

Afghan President Ashraf Ghani gave a stern condemnation of the CIA torture detailed in the report, saying it violated "all accepted norms of human rights" and were part of a vicious cycle of violence.

The report comes with the Taleban insurgency against Ghani's government still resilient, with a series of strikes in heavily-fortified Kabul.

Militants have targeted foreign guest houses, embassy vehicles, US troops and Afghan army buses in Kabul over the past month, undermining claims that the insurgency is weakening as Nato's 13-year war ends.

US Defence Secretary Chuck Hagel said on a visit to Kabul at the weekend that the upsurge showed "that the international community must not waver in its support for a stable, secure, and prosperous Afghanistan".

Hagel insisted Afghanistan would not go the way of Iraq, where another US-trained army virtually collapsed in the face of an onslaught by Islamic State in Iraq and Syria (ISIS) militants after American troops left the country in 2011.

But a day later, Afghanistan's chief executive Abdullah Abdullah told Britain's Sunday Times newspaper that Western forces were leaving prematurely.