A bill to legalise casinos in Japan is facing yet more delays as pro-casino lawmakers struggle to gain enough support in the ruling coalition.

Lawmakers had planned to submit the bill, which failed to pass through parliament last year, by the end of the fiscal year on Tuesday. However, they are still lacking the support of a junior partner in Prime Minister Shinzo Abe’s coalition.

"It's vital to have all the parties in the integrated resort parliamentary league on the same page," Takeshi Iwaya, a senior member of the group from Abe's Liberal Democratic Party was cited as saying by Reuters.

"I won't comment on when we can submit the legislation, but we want to proceed promptly, as soon as the groundwork is done," he said.

The lawmakers are now hoping to present the bill in April, though reportedly there is still strong doubt that the framework legislation will be approved before the end of the current Diet session in June.

Operators keen to gain a foothold in what is expected to rapidly become the world’s third-biggest casino market had hoped for an early passage of the bill to allow them to open in time for the 2020 Olympics in Tokyo.

However, the bill is facing opposition from some politicians concerned about social ills. It is also being held up by more pressing legislation on the parliamentary agenda.