Ebola could spread globally if the world does not respond to the epidemic in Africa, Barack Obama has warned.

The President also said US monitoring of ebola must be "much more aggressive".

He insisted the second case of an infected nurse in Dallas highlights the need to ramp up efforts to confront the disease that has struck West Africa and has reached US shores.

The President spoke after meeting top Cabinet officials involved in the ebola response both in the US and in the West African region where the disease has been spreading at alarming rates.

He said the outbreak must be attacked at its source in west Africa as, if it is allowed to rage there, it will spread globally.

Obama called aid to help the countries worst affected "an investment in our own public health".

More than 4,400 people have died in ebola-hit Sierra Leone, Liberia and Guinea since the latest outbreak took off earlier this year.

At least 15 other countries, mostly in Africa, have already placed restrictions on the entry of people who have recently visited the affected areas according to medical group International SOS.

US House of Representatives speaker John Boehner said on Wednesday that Mr Obama should "absolutely consider" a ban on flights to the US from countries worst affected by the virus.

He said: "A temporary ban on travel to the United States from countries afflicted with the virus is something that the president should absolutely consider along with any other appropriate actions as doubts about the security of our air travel systems grow."

British Prime Minister David Cameron said following the call that the "leaders agreed that this was the most serious international public health emergency in recent years and that the international community needed to do much more and faster to halt the rise of the disease in the region." 

Meanwhile, The UN Security Council called on the international community to "accelerate and dramatically expand" aid to combat the spread of the disease.