KABUL (AFP) - Two Taleban suicide attacks just an hour apart killed one person and wounded five in Kabul on Tuesday, as an Afghan delegation travelled to Pakistan for talks with the militants.

Insurgents attacked a Nato convoy and an office of the Afghan spy agency in the capital as the Taleban pressed ahead with their bloody summer offensive despite recent moves towards dialogue.

President Ashraf Ghani said on Twitter that a team from the High Peace Council (HPC), the body tasked with opening talks with the Taleban, had gone to Islamabad to meet the militants.

There have been several informal meetings between the Taleban and Afghan officials in recent months as Kabul seeks a negotiated end to the insurgents' 13-year fight.

But there have been no major breakthroughs and the militants have kept up their barrage of attacks on foreign and Afghan forces.

In Tuesday's first incident, a suicide car bomber targeted a Nato convoy, wounding three people including one described by the police as a "foreigner".

An hour later three Taleban attackers tried to storm a branch office of the National Directorate of Security (NDS), Afghanistan's main intelligence agency.

One militant on a motorcycle blew himself up, killing a guard, before other guards killed two further attackers.

It is the third time in three weeks that the Afghan capital has come under significant attack, and a week ago another Nato convoy was hit by a suicide bomber on the road to the airport.

The Taleban claimed the attacks in messages on their Twitter account, and Nato confirmed the attack on its convoy, adding that no foreign forces were killed.

NASCENT DIALOGUE

The Taleban leadership have not officially confirmed they will take part in the Islamabad talks, but one militant source told AFP they would attend, saying the Islamabad round would be an extension of meetings held in China in May.

Ghani's deputy spokesman Sayed Zafar Hashemi said the HPC delegation was being led by deputy foreign minister Hekmat Khalil Karzai but gave no further details.

Official efforts to open negotiations with the Taleban have borne little fruit so far, but informal talks have taken place several times recently, veiled in secrecy.

There have been meetings in Qatar, where the Taleban, once notorious for their misogynistic policies, reportedly made conciliatory noises on women's rights, and more recently in Norway.

But holding talks in Pakistan, if they go ahead, would mark a shift. Afghanistan's eastern neighbour has historically supported the Taleban and senior leaders are believed to be hiding out there.

Many Afghans accuse Pakistan of maintaining links to the Taleban in the hope of keeping influence in the country.

Since he came to power last year, Ghani has expended significant political capital to court Islamabad in order to try to get them to persuade the Taleban to come to the negotiating table.

However, the Taleban have laid down hardline preconditions for taking part in full-blown negotiations, stressing the need for the complete departure of foreign troops from Afghan soil.

Even if substantive progress were made in Islamabad, talks alone would not necessarily mean an end to fighting on the ground in Afghanistan - a fact highlighted by the attacks in Kabul.

SUMMER OFFENSIVE

Tuesday's violence comes a week after a Taleban suicide car bomber targeted a Nato military convoy on the main road to Kabul airport, killing at least two Afghan civilians and wounding around 17.

A week before that, insurgents launched a brazen attack on the Afghan parliament.

On Monday, Nato confirmed that US forces carried out two drone strikes in Achin district of Nangarhar province, where the Taleban have clashed with purported supporters of the Islamic State in Iraq and Syria (ISIS) group.

An NDS spokesman claimed the ISIS group's "number two" commander in Afghanistan was killed in an air strike in Achin, without confirming if it was a drone strike, while Nato did not confirm the target of the operation.

Afghan officials say ISIS' presence in the country is limited to small groups and factions that have split from the Taleban, but fears are growing that the group is making inroads in the country complicating the prospect of peace in the war-torn nation.

Nato's combat mission in Afghanistan formally ended in December after 13 years, but a small foreign delegation has stayed on to train and support local security forces.

Stretched on multiple fronts and facing record casualties, Afghan forces are struggling to rein in the militants even as the government makes repeated efforts to jump-start peace negotiations.

The Taleban's annual summer offensive, which began in late April, has sent civilian and military casualties soaring and threatened major cities for the first time in a decade.