FACTBOX: Profiles of Afghan presidential candidates

KABUL (Reuters) - Afghanistan is holding a run-off vote in its disputed presidential election on November 7, with attacks mounting and insurgents vowing to disrupt the poll.

President Hamid Karzai agreed to the poll under severe global pressure after a U.N. fraud inquiry invalidated enough of his votes to trigger a run-off. His closest rival is ex-foreign minister, Abdullah Abdullah.

Following are brief profiles of the two candidates:

HAMID KARZAI

Karzai has been the leader of Afghanistan since the Taliban were toppled in a U.S.-led invasion in 2001. Backed by his Western allies but also seen as a unifying force at home, he won the country's first presidential poll in 2004.

Despite criticism over election fraud and souring relations with Washington, Karzai is widely expected to win the second round because, as a Pashtun -- Afghanistan's largest ethnic group -- he has strong grassroots support in the south and east.

In April 2008, he survived an assassination attempt while attending a military parade close to the presidential palace.

Karzai comes from the same tribe as the former Afghan royal family. He received a Masters Degree in political science in India in 1983 and then joined a small pro-monarchist faction of the anti-Soviet mujahideen in Pakistan.

He served as deputy foreign minister after the fall of the Soviet-backed government in Kabul in 1992.

At first supporting the Taliban, Karzai later worked from Pakistan to overthrow the austere Islamists. He returned to Afghanistan in late 2001 when he was appointed president of the country's interim government in a U.N.-sponsored deal in Germany.

Endemic government corruption, slow development, his alliance with former militia leaders and civilian casualties caused by foreign forces have eroded his public support. Karzai says talks with moderate insurgents are his top priority.

ABDULLAH ABDULLAH

Abdullah served as Afghan foreign minister between 2001 and 2006. He is seen as a prominent leader of the ethnic Tajiks in the north while also being half Pashtun.

Abdullah, who is 49-years old, has spearheaded election fraud allegations against Karzai and questioned the vote's credibility.

He has a medical degree from Kabul University and worked as an ophthalmologist until 1985. A year later he joined the Panjshir Resistance Front against the Soviets and served as an adviser to the anti-Taliban General Ahmad Shah Masood.

During his election campaigning for the first round, Abdullah played up his link to Masood, who was assassinated by al-Qaeda agents in 2001 and is now an important figure for many Tajiks.

While working with Masoood, he was appointed foreign minister for the Northern Alliance in 1998 and after Masood's assassination, became a key figure during the alliance's efforts to topple the Taliban alongside U.S. forces.

He was appointed foreign minister under Karzai's interim government, a position he held until Karzai sacked him abruptly in 2006.

(Writing by Maria Golovnina; Editing by Bill Tarrant)