AUSTIN (REUTERS) - Texas Governor Greg Abbott issued an executive order on Monday (Oct 11) barring all Covid-19 vaccine mandates in the US state by any entity, including private employers.

Mr Abbott's move sets him up for a clash with President Joe Biden, a Democrat who last month called on employers nationwide to order their workers to be vaccinated or lose their jobs.

Mr Abbott is a Republican.

"The Covid-19 vaccine is safe, effective, and our best defence against the virus, but should remain voluntary and never forced," he said in a written statement.

The governor's order states that "no entity in Texas" could compel proof of vaccination by any individual, including employees or customers. Mr Abbott also called on state lawmakers to take up the issue in an upcoming special session.

Tech giants Facebook and Alphabet Inc's Google have both told employees that they would need proof of vaccination to return to their offices. Both companies employ large numbers in Texas.

Fort Worth-based American Airlines, the largest US carrier, last week told its 100,000 US-based employees they must submit proof of full vaccination no later than Nov 24 - or be fired.

United Airlines imposed a vaccine mandate on its 60,000 employees, around 9,000 of whom are based in Texas.

The company is defending a lawsuit filed in Fort Worth, and a federal judge on Wednesday will hear a request by United employees for an injunction to prevent the carrier from firing employees who requested exemptions from the vaccine mandate.

Mr Biden's mandate announcement in September came as his administration struggled to control the pandemic, which has killed more than 700,000 Americans.

Mandatory vaccinations have become an incendiary political issue in the United States, with many conservatives saying they amount to government overreach. Proponents argue they are crucial in curbing the spread of the highly contagious virus.