Washington - The US government on Thursday advised Americans to avoid travelling to Yemen following the deadliest attack on a US embassy in more than 10 years.

The US State Department also authorized non-essential staff and their families to depart Yemen and said the security threat remains high because of terrorist activities.

Al-Qaeda is believed to be behind the attack on the embassy in Sana'a that left 16 people dead, including six militants.

US State Department spokesman Sean McCormack confirmed Thursday that a US woman, 18-year-old Susan Elbaneh, was among those killed outside the embassy ground.

The terrorists attacked with two car bombs while other armed men tried unsuccessfully to breach the compound walls.

The Yemeni government on Thursday said it had arrested 20 suspected Islamist extremists in connection with the embassy attacks. (dpa)