Anwar al-Awlaki, the US-born cleric linked to al Qaeda has been killed in Yemen, the country's defence ministry has said.

Awlaki is believed to have died on Friday morning, 90 miles east of the capital Sana'a between the Marib and al-Jawf. It is thought he was killed by an air strike. According to local tribal leaders, the attack came while he was travelling in a two-car convoy.

It is not know if the preacher was targeted by one of the US military drones that operate over Yemen.

Credited with being being the head of Al Qaeda in the Arabian Peninsula, 40-year-old al-Awlaki came to prominence due to his alleged links with a series of terror plots.

The cleric is reported to have had email exchanges with the US Army Major Nidal Malik Hasan, who was responsible for the Fort Hood shootings at a military base in Texas in 2009. The shootings left 13 dead.

In 2009, The Telegraph reported that Hasan had attended the Dar al-Hijrah mosque in Virginia Falls, while Awlaki was there as a preacher.

He is also believed to have had connections with Faisal Shahzad, the 30-year-old Pakistan-born resident of Bridgeport, arrested for the failed car bombing of Times Square in 2010.

The US accused Awlaki of being linked to the failed attempt to blow up a plane over Detroit on Christmas Day, 2009. Umar Farouk Abdulmutallab, a 23-year-old Nigerian, tried to down an aircraft by igniting a bomb concealed in his underwear.

In February 2010, Awlaki gave an interview to Al Jazeera in which he said he supported Abdulmutallab's attempted attack but did not encourage it.

Speaking to the channel, he said: "Yes, I support what Umar Farouk has done after I have been seeing my brothers being killed in Palestine for more than 60 years, and others being killed in Iraq and in Afghanistan.

"And in my tribe too, US missiles have killed 17 women and 23 children, so do not ask me if al-Qaeda has killed or blown up a US civil jet after all this. The 300 Americans are nothing comparing to the thousands of Muslims who have been killed."

When asked if the Yemeni government would facilitate his assassination, Awlaki said:

"The Yemeni government sells its citizens to the United States, to earn the ill-gotten funds it begs the West for in return for their blood."

British foreign secretary William Hague said if confirmed, Awlaki's death would be "another significant blow to al Qaeda".

"With the attempted Detroit bombing and the aeroplane cargo bomb plots he has demonstrated his intent and ability to cause mass terror, whilst his murderous ideology was responsible for inspiring terrorist attacks in the UK and the US," he said on Friday.

According to US intelligence, Awlaki acted as the spiritual leader to three of the 9/11 hijackers and, until 2009, ran and updated a blog that espoused an extreme Islamic ideology.

He was also suspected of involvement with plots to attacks interests in Europe and the UK. In 2010 MP Stephen Timms was approached and stabbed by 21-year-old Roshonara Choudhry in Beckton, East London. The motive for the attack, according to Choudhry, was the MP's support for the Iraq war, however she said she had been inspired by the preaching of al-Awlaki.

Rajib Karim, the 31-year-old software engineer who was jailed in 2010 for plotting to blow up a British Airways plane, had corresponded with Awlaki on his intent to place a package on a US-bound flight.

In 2009, the preacher was controversially invited to speak via video link-up by City University's Islamic Society, however after media attention and pressure by the Centre for Social Cohesion, the event was cancelled.

Born in New Mexico in 1971, Awlaki grew up in Yemen but returned to the US to attend university.

He has been reported dead before, most recently in 2009. In April 2010, the cleric was added to the CIA's kill or capture list by the Obama administration after a special government review concluded that he had played an operational role in attempted terrorist attacks on the US. He was the only American on the hit list.