The US Secret Service is investigating an online survey that asked whether people thought President Barack Obama should be assassinated.

The poll, posted on Monday on Facebook, was taken off the popular social networking site quickly after company officials were alerted to its existence.

But, like any threat against the president, Secret Service agents are taking no chances.

The poll asked respondents "Should Obama be killed?" The choices: No, May be, Yes, and Yes if he cuts my health care.

Facebook says the question was not created by the company, but by an independent person using an add-on application that has been suspended from the site.