Dozens of businesses and landlords outraged over the delayed light rail project from Sydney's CBD to the eastern suburbs have filed a class action lawsuit against the NSW government.

The case, which has more than 60 claimants so far, was filed in the NSW Supreme Court on Tuesday morning and seeks millions in compensation from the government over “poor” planning decisions.

The business owners say the state government’s multi-billion dollar light rail project has caused them “substantial” loss and damages, Mitry Lawyers said in a statement on Tuesday.

Sophie Hunt, of Hunt Leather on George Street, has seen sales decline by 50 per cent since construction works began in October 2015.

“The effect has been devastating (with) horrendous dust, staff with migraines, bleeding noses, ear pain, asthma attacks, how can you sell in that condition?” Ms Hunt told reporters outside the Supreme Court.

“Of course I’m angry, we were perfectly fine. We’ve had to sack people, we’ve had to take on a second mortgage through no fault of our own – if it had have been six to eight months (as promised) we would have been fine.”

Ms Hunt said her business had been affected for more than two-and-a-half years.

Lawyer Rick Mitry argued his clients have a strong case against Transport for NSW.

“Quite frankly, to see the despair on some of their faces disturbed me,” Mr Mitry said on Tuesday.

“Their businesses were destroyed and they were destroyed.”

The class of 60 businesses is expected to grow as the case gains momentum.

The lawsuit is the latest in a string of legal actions hanging over the light rail project to Randwick and Kingsford.

Spanish sub-contractor Acciona is seeking an extra $1.2 billion saying it was misled over the complexity of the project.

Queensland-based contractor VAC Group is seeking $4 million plus damages from the government because of alleged misleading and deceptive conduct.

The light rail was meant to be finished in 2019 but main contractor ALTRAC told the government in April the new completion date was March 2020.

The project was originally budgeted to cost $1.6 billion before a $500 million blowout.

Transport Minister Andrew Constance is disappointed the businesses have resorted to court action.

“I’m sad that it has got to this,” he told reporters in Sydney.

“I have to acknowledge it has been incredibly hard on a lot of business people who have been subjected to lengthy closures outside of their business doors as a result of that construction.”

Mr Constance noted the coalition has handed out $9 million in rental assistance to 90 businesses. He said on Tuesday the chequebook remained open.

NSW Premier Gladys Berejiklian isn’t fazed by the controversy stating last week she’s “not concerned at all” about the “amazing project”.

By Tom Rabe