Republican lawmakers in California have formally demanded that state Attorney General Rob Bonta open an investigation into the California High-Speed Rail Authority over expenses they describe as illegal, escalating a long-running political fight over the state's bullet train programme.

The request, reported by The San Joaquin Valley Sun, targets the authority's handling of funds for the Los Angeles–San Francisco high-speed rail project, which has been under construction in the San Joaquin Valley for more than a decade.

What are the lawmakers alleging?

The GOP legislators contend that the High-Speed Rail Authority has spent money in ways that violate state law, and they want Bonta's office to determine whether the agency misused public funds. Their demand adds a legal dimension to what has so far been primarily a legislative and oversight dispute.

Critics of the programme in the state legislature have repeatedly questioned the authority's cost estimates, schedule commitments and contracting practices. The call for an attorney general investigation raises the stakes by seeking a formal law enforcement review rather than routine audits.

Who is involved?

• Republican members of the California legislature, who are pressing for the probe.
• Attorney General Rob Bonta, whose office would carry out any investigation.
• The California High-Speed Rail Authority, the state agency building the project.

What happens next?

The decision on whether to open an investigation rests with Bonta's office. The authority, for its part, has consistently defended its compliance with state funding requirements in past oversight disputes.

Any probe would add scrutiny to a project that remains central to California's rail ambitions, with construction continuing in the Central Valley while funding battles play out in Sacramento and Washington.