KABUL - Two Taliban suicide attacks hit Kabul on Thursday, one targeting a play at a French-financed school, killing at least seven people including a German national just as Nato forces are due to pull out of Afghanistan.

A teenaged bomber targeted the Kabul auditorium packed with people watching a drama condemning suicide attacks killing a German man and wounding 16 people, officials and a witness said.

The suicide blast was the second to strike the Afghan capital in a day, after six Afghan soldiers perished when their bus was hit on the outskirts of the city as they rode into work. The violence came less than three weeks before the year-end deadline for most foreign combat soldiers to withdraw from the country.

General Ayoub Salangi, head of the Interior Ministry while the cabinet is being finalised, said the suspected theatre bomber appeared to have been about 17 years old and detonated his explosives at the venue during an early evening performance. "I heard a deafening explosion ... There were Afghans, foreigners, young girls and young boys watching the show," Sher Ahmad, an Afghan rights activist who was at the performance, told Reuters.

He said the blast came during a performance of a new play called "Heartbeat: Silence After the Explosion", a condemnation of suicide attacks. "Pieces of flesh were plastered on the wall. There were children and women crying for help. Some were running out, some were just screaming." Taliban spokesman Zabihullah Mujahid said the bomber targeted the event because it was staged "to insult Islamic values and spread propaganda about our jihad operations, especially on suicide attacks".

Amid confusion immediately following the blast, one person could be heard saying "It's all part of the show" in a video posted on YouTube purporting to be of the attack.

Early police reports said the bomber attacked the French-run Lycée Esteqlal, one of Kabul's oldest and most highly respected high schools, but Ahmad said the performance was at the French Cultural Centre located in the same compound. Salangi said the person confirmed killed was a German man, but he could not immediately confirm his identity. German Foreign Minister Frank-Walter Steinmeier said the attack was "particularly perfidious because it ... was against exactly those people who are helping the country to build a better future."

The French government said in a statement that "several" people were killed in the attack and "many" more injured, but none of the fatalities were French nationals. The venue was heavily guarded during the event, according to Kabul police chief Abdul Rahman Rahimi, who added that the bomber may have hidden explosives in his underwear to pass through security.

He said the bomber detonated the explosives at the top of the auditorium stairs, which may have prevented more casualties. The body of the bomber was shredded, but police were able to identify him as a teenager because his head was found intact.

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. French President Francois Hollande condemned the bombing as "heinous" and said it was an assault on "culture and creativity."

Earlier on Thursday, the bomber who was on foot targeted a bus carrying Afghan troops in Tangi Tarakhil on the outskirts of the capital, Afzail told AFP. "As a result of the (first) attack, six Afghan soldiers 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.

Five Afghan school children were also reported killed in a foreign forces airstrike in northern Parwan province, Afghan officials said. The International Security Assistance Force confirmed an air strike in the area, but said five insurgents were killed. Civilian casualties caused by air strikes have been one of the most contentious issues of the war, although there are often conflicting claims.

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 December 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, 25 miles 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.

- Taliban resilient -

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 Taliban 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 Defense 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 jihadists 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.