Speaking on a BBC Radio Wales phone-in, Morgan said money had been “poured” into HS2 which had been classed as a England and Wales project, “even though not one inch of track was laid in Wales”.
She said that was a “fundamental injustice”.
“For the first time, the UK government has recognised that we have been underfunded,” she said.
Morgan said conversations had “already started” on a “long list of projects” that could be invested in.
Morgan, asked if there would be consequential funding from HS2, suggested it would not: “It would probably be in the shape of new stations.”
In a letter to the Welsh government from UK government Transport Secretary Heidi Alexander, and Welsh Secretary Jo Stevens, the ministers said: “We recognise that railways in Wales have seen low levels of enhancement spending in recent years, particularly in the context of major investments such as HS2”.
The letter made clear that decisions on extra cash will be up to the Treasury, saying that the Chancellor Rachel Reeves “has been clear on the position of the public finances bequeathed by the last government”.
She said the prioritisation of rail service projects proposed by the Welsh Rail Board, which the two governments are a part of, will inform work with the Treasury ahead of the spending review, due in the Spring.