Customers, tariffs and taxation are the leading Brexit concerns for businesses in Northern Ireland, economic development agency Invest NI has said.
They made up 38% of support requests to Invest NI from businesses about Brexit.
People movement and immigration was second on the list, accounting for 23% of all requests, followed by strategic sourcing (14%), transport and logistics (11%), and regulations and standards (8%).
Business capability advice accounted for 4% of support requests while financial and currency management made up 1%.
Donal Durkan, executive director of strategy at Invest NI, told the Assembly's economy committee that the agency had held 19 Brexit information events, which had been attended by 2,200 businesses.
This included nine one-to-one Brexit advice clinics, which had been attended by 300 businesses, resulting in 475 one-to-one sessions altogether.
Invest NI said that in future it was focused on extensive business engagement, identifying companies most at risk from Brexit and research to understand customs capacity issues in Northern Ireland.
Mr Durkan said Invest NI had worked with 1,500 firms "intensively", but that advice and support was open to all.
"That would be our core businesses that we provide financial support to as they export into other markets, but any business that makes contact with us will get directed to the workshops, online assessment tool and access to specialists," he added.
"Around 72% of all businesses we deal with intensively are micro or SMEs.
"Most of our work is with firms employing less than 50 people.
"I wouldn't have concerns that small or micro businesses don't understand the issues around Brexit or where to turn for advice."
Mr Durkan explained that the main challenges around Brexit will be for those businesses "who haven't experienced import and export declarations before".
"The difficulty for smaller businesses is they don't have the resources," he said. "The NI protocol won't be resolved until June of July so the timescale to put into place what they need to do will be short."
Invest NI also said that the level of foreign investment and interest has not been diminished by Brexit as companies come to Northern Ireland for services in addition to their main office function.
"Businesses don't come here for access to the EU or Great Britain market so that level of investment and interest has not disappeared due to Brexit," Mr Durkan said.
But Sinn Fein MLA John O'Dowd said there was a need for increasing foreign direct investment outside of Belfast.
He listed Londonderry and Newry as potential locations as well as Craigavon, Portadown and Lurgan, which he said were along the railway line and already had good road infrastructure.
In response Mr Durkan said that Invest NI promotes Northern Ireland as a location but not "individual elements of it".
He added that "two-thirds of investment and jobs are outside Belfast" and that there had been 20,000 new jobs created in the last five years.
The meeting comes just a day after it was revealed Belfast had fallen down the rankings of European cities in a report on preferred investment destinations.
FDI Intelligence, a specialist division within the Financial Times, produces analysis measuring the strength of cities in attracting foreign direct investment.
Belfast was recognised as the second best city in the world for its FDI strategy in December 2018.
However, a year after being ranked as the best mid-small city in the world for business friendliness, it's now at number eight on the list.