Prime Minister Robert Abela on Thursday played down differences between his finance and mobility ministers over the proposed €2.8 billion light rail project, insisting their positions were not contradictory and that the project's viability must be established before the government can proceed.

Abela was responding to journalists after Finance Minister Clyde Caruana said on Tuesday that he had yet to see the studies underpinning the light rail proposal announced by the government shortly before the election, and that he was not yet convinced the country could afford it.

The project was announced with some fanfare by then transport minister Chris Bonett in April. He said it would cost €2.8 billion, including a contingency of between 40% and 45% to cover potential risks.

Abela said he understood the perspectives of both ministers and insisted they were not at odds.

"This would undoubtedly be the largest infrastructure project our country has ever undertaken, and probably the largest it will ever undertake," he said.

The prime minister said preparatory studies were currently being carried out and would eventually provide a clearer picture of the project's feasibility.

He also pointed out that Caruana had allocated the necessary funding for these studies.

"As these studies progress to more advanced stages, we will be in a position to provide updates at each stage, including on the project's viability."

Abela said establishing viability was particularly important for a project costing billions of euros.

"These are precisely the assessments that must be carried out beforehand," he said.

"There are challenges, and I want to be very clear about that. I am certainly not underestimating the traffic problem or pretending that it does not exist."

Construction of the proposed 24-kilometre light rail line linking the airport to St Paul's Bay is expected to begin five years after the project was announced in April.

The section between the airport and Valletta is expected to take "three, maximum four years" to build, with services beginning within the next decade.

The full line is expected to be completed within 15 years and would form the backbone of the government's Malta in Motion plan to redesign Malta's transport network.