A $500,000 sports grant was awarded to a politically-linked football body in a marginal Liberal seat to build an amenities building that was already slated for construction thanks to an earlier $800,000 grant from the New South Wales government.

The much-criticised federal sports grants scheme awarded $500,000 to the St George Football Association to fund the construction of an amenities building at Gannons Park in Sydney, home to multiple clubs and a large number of players.

The club sits in the marginal electorate of Banks, a key seat for the Liberals, which held it by a razor thin 1.4%.

The money was awarded after the NSW government gave $800,000 for the same building in July 2018.

When the NSW government announced its money, the local council said the work was planned to begin in October 2018, would progress through 2019, and finish in 2020.

No mention of the need for any federal money was made.

The federal grant was not decided until December 2018 and was publicly announced weeks before the May 2019 election by the immigration minister, David Coleman, the local MP for Banks.

Coleman has also been the club’s patron for several years.

The football association has links to federal and state MPs from both major parties. Its website says the association’s patrons include Coleman, former Liberal MP Nickolas Varvaris and Labor MP Linda Burney, as well as state Liberal MP Mark Coure, and state Labor MPs Steven Kamper and Chris Minns.

The sports grants rules prohibit money going to projects where work had already commenced, rules designed to ensure federal funding is directed to where it is most needed.

The Georges River council says work did not actually begin work on the building until October 2019, meaning it would not have breached the sports grants formal eligibility requirements.

The federal sport minister, Richard Colbeck, said the grant application stipulated the work would cost $1.48m. He said the application detailed plans for co-funding by the council, state government and the association.

“The application was supported by the appropriate documentation, including consent from the George’s River council, a project summary and estimated costings,” he told the Guardian.

A spokeswoman for the Georges River council said the use of multiple funding sources was common.

She said the amenities building was substantial, and included the provision of separate club facilities, multiple change rooms, a canteen, storage spaces, clubrooms, and covered viewing areas.

“The Gannons Park clubhouse construction contract is valued at $1,808,000.00,” she said.

“The new clubhouse is double the size of the original clubhouse, in order to accommodate the two soccer clubs and their large membership base.”

“The facility also includes fully disabled-compliant public amenities and a large service room to house critical infrastructure which supports the operation of the playing fields.”

The St George Football Association was approached for comment but did not respond.