Media playback is unsupported on your device Media caption In his video message, President Obama urged Americans not to "give in to hysteria or fear"

US President Barack Obama has ruled out imposing a travel ban on Ebola-hit countries of West Africa.

He said isolating an entire region, a move urged by some Republicans, would make the situation worse.

Mr Obama urged Americans not to give in to hysteria, stressing that the two cases contracted in the US were not an epidemic or an outbreak.

The virus has killed about 4,500 people in Guinea, Sierra Leone and Liberia, according to the UN.

Mr Obama said the best way to tackle the disease was at its source, before it spreads.

"Trying to seal off an entire region of the world, if that were even possible, could actually make the situation worse," he said.

"It would make it harder to move health workers and supplies back and forth.

"Experience shows that it could also cause people in the affected region to change their travel, to evade screening, and make the disease even harder to track."

He stressed that the US was not in the middle of an outbreak or an epidemic and urged Americans to stay calm.

However, the New York Times has reported that the president was furious with his aides over an inadequate response to the disease.

The newspaper said medical officials had given information that turned out to be wrong, local guidance was inadequate and categories of threats were unclear.

Image copyright Science Photo Library Image caption Boarding school medical staff are expected to keep up-to-date with the latest government guidance

How not to catch Ebola:

Avoid direct contact with sick patients as the virus is spread through contaminated body fluids

Wear goggles to protect eyes

Clothing and clinical waste should be incinerated and any medical equipment that needs to be kept should be decontaminated

People who recover from Ebola should abstain from sex or use condoms for three months

Ebola basics

How Ebola attacks

What virus has hit - in maps

Uncertainty over figures

Image copyright AFP Image caption At least one protester has been attempting to put pressure on the government to impose travel bans

Some 60 Republicans in the House of Representatives have informally said they would support a travel ban, according to an unofficial count on the Hill website.

They were joined by a handful of Democrat representatives and a small number of Republicans in the Senate.

Republican House Speaker John Boehner, who supports travel restrictions, has hinted that he may propose a vote on the issue.

Several US airports have begun screening for Ebola, despite experts saying such moves were unlikely to have an impact.

Two American nurses contracted the virus after treating a Liberian man who subsequently died of the disease at a hospital in Dallas.

The nurses - Nina Pham and Amber Vinson - are receiving treatment and were said to be stable on Friday.

In other developments: