The killing of al Qaeda chief Osama bin Laden has led to a direct threat by militants on a relative of US President Barack Obama.

ABC News reported that Al Shabaab, a Somali-based al-Qaeda organization has threatened to kill Obama’s 88-year-old Kenyan grandmother, Sarah Onyango Obama.

On Wednesday, Omar Hamami, a senior Shabaab official, warned: We are sending a message to [Barack] Obama and [Secretary of State] Hillary Clinton that we will avenge the death of our leader Sheikh Osama bin Laden very soon. Osama is dead but the holy war is not dead. Mujahedeen fighters all over the world are fully prepared to revenge the death of our leader.”

The threat is being taken so seriously that she has received round-the-clock security.

We received reports of plans to attack the home of Mama Sarah Obama, and we immediately put in place adequate security measures, police chief Stephen Cheteka told the African Review, a Kenyan newspaper.

Sarah Obama, who lives in the village of Nyang'oma Kogelo, in western Kenya near the Ugandan border, was the second wife of the Barack's late grandfather, Hussein Onyango Obama, thus she is not biologically related to the US president.

All visitors going to [Sarah Obama’s] home will have to be thoroughly vetted. They will undergo security screening before they are cleared to visit the home, another Kenyan security official told media.

Everybody, including relatives, must comply to make the work of security personnel easier. On top of the security that was given, we will also provide more security in terms of escort for Mama Sarah.

However, Sarah is apparently unconcerned about the threats and the heightened security.

My life has not been affected in any way, she told ABC News. It has not restricted my movement. If the government has decided to bring more security personnel, we are OK with it.”

Shabaab has long fought the Western-supported government in Somalia for several years and reportedly large portions of the lawless nation which borders Kenya.

Kenya was already on alert prior to the latest threat.

In 1998, al-Qaeda attacked US embassies in East Africa, including Nairobi, Kenya, where at least 213 were killed.