Concern is boosting its presence in the West African country
The Irish Government has announced emergency funding for Sierra Leone following deadly mudslides earlier this week.
While numbers of casualties have not been confirmed, at least 3,000 people are believed to have lost their homes and are in immediate need of assistance and shelter.
Several thousand people are still missing.
Foreign Affairs Minister Simon Coveney said: "I am deeply saddened by the deaths and destruction caused by the flooding and mudslides in Sierra Leone and extend my condolences to the people and Government of Sierra Leone.
"Through our embassy in Freetown, we are liaising closely with our partners on the ground, including the Sierra Leonean government, to ensure an effective and urgent response to this disaster.
"Ireland's pre-positioned funds with NGO and UN partners are available for use to meet the needs of those affected."
A crisis alert of more than €400,000 has already issued from the Start Fund to provide funding.
The Start Fund is a humanitarian pooled fund which enables NGOs to access emergency funding in order to quickly respond to emergencies.
Ireland allocated €1.3m to the Start Fund earlier this week.
Last year, through its embassy in Freetown, Ireland provided €6.64m in bilateral development assistance through the UN and NGO partners in Sierra Leone.
Meanwhile Irish aid agency Concern Worldwide is boosting its emergency response team in the West African country.
The aid agency already has 157 staff working in the capital, Freetown.
The charity says mortuaries are overwhelmed, thousands of people have been left homeless and there are fears that diseases such as cholera and typhoid may spread.
Speaking from flood-damaged Freetown, Concern's national health coordinator in Sierra Leone, Adèle Fox, said: "Bridges were destroyed, whole areas of housing were completely wiped away and many people buried within all of that mud.
"Concern Worldwide is part of a consortium of aid agencies working together and with the government doing assessments and addressing immediate needs."
Ms Fox said the immediate needs now and over the coming days will include logistical support, hygiene items, tarpaulins for shelter and water.
The country's President Ernest Bai Koroma has declared a period of national mourning until Tuesday August 22nd.
A national minute silence was also held there at midday on Wednesday.
The President of #SierraLeone has declared period of national mourning from today to Tuesday 22. National minutes silence at midday today.— Embassy Freetown (@IrlEmbFreetown) August 16, 2017
The Irish embassy in Freetown can be contacted on +232-79-250-623. However, there are no reports of any Irish citizens affected.
In updated travel advice, the Department of Foreign Affairs says Irish people there should exercise a high degree of caution.
It is advising them to take extra caution when driving, as road conditions have deteriorated.
Sierra Leone was declared Ebola free in March 2016, but the department says visitors should exercise vigilance.
Reporter Rebecca Williams, in the capital Freetown, says she has been told that more than 500 bodies have now been brought to the city's morgue.
Williams said: "Thousands of houses have been flattened. All that remains among the rubble are the clothes from washing lines flattened in the mudslides.
"Enormous boulders have wiped out properties here that were four storeys high.
"As the hours go by, yet more stories of loss emerge. Four local football teams are among those who died.
"At the local mortuary, horrific pictures show bodies piled up on top of each other, battered and bruised."
The UN said it was evaluating needs in the country and that "contingency plans are being put in place to mitigate any potential outbreak of waterborne diseases such as cholera, typhoid and diarrhoea".
Additional reporting: IRN