Media playback is unsupported on your device Media caption Tulip Mazumder spoke to army medics travelling to Ebola-hit countries

About 100 soldiers from the Royal Army Medical Corps are travelling to Sierra Leone as part of the UK's efforts to tackle the Ebola outbreak.

International Development Secretary Justine Greening will join the medics to see how Britain's £125m aid package is helping to combat the deadly virus.

Her visit to West Africa comes as the UN said a third member of its staff in Sierra Leone had died from the disease.

In the UK, Gatwick has begun screening air passengers from at-risk countries.

The outbreak has killed more than 4,500 people in West Africa, with Liberia, Guinea, and Sierra Leone the three worst-affected countries.

On Monday, the World Health Organization (WHO) declared Nigeria - West Africa's most populous nation - officially free of the virus after six weeks with no new cases. It comes after WHO officially declared Senegal Ebola-free on Friday.

'Vital supplies'

Cabinet minister Ms Greening left RAF Brize Norton in Oxfordshire on Tuesday morning with the medics from Catterick-based 35 Squadron, 5 Armoured Medical Regiment and the Royal Army Medical Corps.

They will staff an Ebola training academy alongside some 90 personnel from 22 Field Hospital who left for Sierra Leone last week.

Ms Greening will visit the academy and the site of a 92-bed treatment facility in Kerry Town, which is in the final stages of construction.

Image copyright EPA Image caption The UK is leading the international effort in Sierra Leone

She said: "Halting the disease in West Africa is the most effective way of preventing Ebola infecting people here in the UK.

"That is why we are providing 700 treatment beds in Sierra Leone, sending vital supplies such as chlorine and protective clothing, and training hundreds of health workers.

"I look forward to seeing for myself how British army medics and engineers, as well as our humanitarian and health workers, are spearheading the UK's efforts to contain and ultimately defeat Ebola."

Image copyright AP Image caption Ms Greening is joining British troops heading to Sierra Leone

The UK is leading the international response to the disease in Sierra Leone, where it has pledged a £125m aid package.

In all, Britain is deploying 750 military personnel, including the Royal Navy's casualty ship RFA Argus.

European countries have committed more than 500m euros (£400m; $600m) - but the UK is pressing for that amount to be doubled.

Image copyright AFP/getty images

The UN has said the outbreak is the most serious health emergency of modern times.

BBC international development correspondent Mark Doyle said the British contribution was significant, but it has come "very late" despite warnings from medical charities as early as April.

Ghana's President John Mahama, meanwhile, has said vital supplies and resources to tackle Ebola are now beginning to reach the three worst-hit West African countries.

Mr Mahama told the BBC that the World Food Programme was airlifting humanitarian aid to Liberia, Sierra Leone and Guinea.

In the UK, screening for passengers from affected countries started at Gatwick Airport on Tuesday, beginning at the north terminal and to be rolled out to the south terminal by the end of this week.

It comes after Heathrow began screening last week. Screening for Eurostar passengers arriving at London's St Pancras station, along with passengers at Birmingham and Manchester airports, is expected to start soon.

UK Ebola mission in Sierra Leone £125m Pledged by UK to help fight disease 780 British health staff volunteers helping to cope with the crisis

700 Hospital beds supported by UK - tripling Sierra Leone's capacity

750 Military staff to help construct treatment centre and other facilities

100 Beds on board medical ship RFA Argus being deployed to region Reuters

Ebola virus disease (EVD)

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