About 100 businesses in Newry have been affected by flooding, with some suffering "catastrophic" damage, a business group has said.
Eamon Connolly, of Newry Business Improvement District, said there had been significant cost to businesses
Earlier, Shadow Northern Ireland Secretary Hilary Benn said the flooding was a crisis and current government support was not enough.
He compared it with the support given to people in England after Storm Babet.
"People are in trouble, they need help, it's very simple," Mr Benn said.
Mr Connolly said businesses were facing costs from damaged premises, stock and fixtures and fittings and loss of turnover.
He said his group was trying to provide practical help in terms of cleaning, recovering stock that had not been destroyed and helping people access premises safely.
"There has been a great outpouring of civic support and we have offers of space from storage to trading premises across Newry and we are actively working to try and relocate businesses," he said.
Paul McCartan of McCartan Bros menswear said he had had many offers from people in the city offering temporary premises.
"I need to be going into a premises that is fitted out for retail, for clothing, rather than going in to a blank unit and having to spend money that I don't have to kit it out," he added.
"So we are in the process of trying to get something over the line on that, it's with legals now and it's just taking time."
Florist Karen Sherwin said her business had got back online for deliveries and collections.
"We're doing what we can here. The shop's been cleared out - four days of cleaning and clearing - fresh flowers in today," she said.
In Portadown, a flood advice centre was opened in the town hall over the weekend.
There was a fantastic response from residents & businesses to the Flood Advice Centre at Portadown Town Hall over the weekend.
The centre will be open today Monday, 6 Nov, 10am - 12pm & 5pm - 7pm, to provide one-to-one support & advice. For info visit: 👉https://t.co/QWdBB2waqQ pic.twitter.com/PmwJPeFaU1
— ABC Council (@abcb_council) November 6, 2023
Just outside the town, repair garage owner Adrian McKernan told BBC News NI that he woke on Wednesday morning to find about a dozen sandbags had been left at the gate by the council.
He said when the River Bann burst its banks that evening, he realised these would be of little help against the rising waters and that no further assistance would be coming from the council.
Taking matters into his own hands, he hired a pump and bought large quantities of sand to fill hundreds of his own sandbags at a cost of about £2,500.
He said as his home was not flooded he has been told by officials he may not be eligible for compensation.
"If you save your home, you're not getting the money. If you let your home flood they'll give you £1,000," he said.
Donatas Petryla's parents' home on Park Road in Portadown was damaged by about 1m (3ft) of flood water.
He said they did not have insurance for flooding and were eligible for support of £1,000.
He said his parents, who are holiday, would be devastated when they return.
Another town hit by flooding last week was Downpatrick, which was visited by Sinn Féin deputy leader Michelle O'Neill on Monday.
She reiterated her calls for the UK government to step in "immediately" and provide a financial support package for businesses.
Earlier, speaking to BBC Radio Ulster's Good Morning Ulster programme, Mr Benn said a number of schemes were announced for victims of Storm Babet in England.
"In Northern Ireland, all there is at the moment is the scheme of emergency relief that has been activated," he said.
"That means homeowners, but not businesses, can get £1,000 - and that is not enough."
On Saturday, Mr Benn wrote to Northern Ireland Secretary Chris Heaton-Harris to ask what assistance the government could provide to businesses and homes in Northern Ireland.
In a statement on Monday, Mr Heaton-Harris said his department was "ready to support and provide assistance where possible".
"We continue to work very closely with the Northern Ireland Civil Service to get the best information on the scale of the impact and to explore options to support businesses which have been hit by flooding, and we are in touch with the NI parties on this," he said.
Democratic Unionist Party leader Sir Jeffrey Donaldson whose party withdrew from government in protest at post-Brexit trading rules said he was aware of the harm and damage caused by the flooding and that party representatives are "engaging with councils and local businesses".
Meanwhile, there is disruption to bus services around several schools in the Newry, Mourne and Down District Council area as a result of flooding.
Among those schools affected by the travel disruption are St Louis Grammar School Kilkeel, St Mark's High School Warrenpoint, Kilbroney Integrated Primary School, Shimna Integrated College, St Colman's College Newry and Sacred Heart Grammar School Newry.
The Education Authority (EA) has advised that some services to and from these schools will not be operational from 6 November to 10 November.
In a statement, the EA said: "We recognise the impact this has on children, young people and their families, and will continue to work at pace to ensure all routes return to normal schedules as soon as possible."