A US federal judge has temporarily blocked a bill introduced in Texas that the US government says amounts to an effective ban on most abortions in the state.

The US Department of Justice began the legal action last month, with Attorney General Merrick Garland saying that the lawsuit was aimed at preventing Texas from enforcing Senate Bill 8 (SB8), which came into effect on 1 September.

US District Judge Robert Pitman’s ruling prevents the state from enforcing the Republican-backed law, which prohibits women from obtaining an abortion after six weeks of pregnancy, while the legal battle over its legality continues.

Texas to appeal

"This court will not sanction one more day of this offensive deprivation of such an important right," Pitman said in the ruling.

The state of Texas has already filed an appeal, according to reports from the US.

The US Supreme Court (pictured) had allowed the measure to proceed, but the US government had argued that SB8 was invalid under the US constitution, and was pre-empted by federal law.

According to the US government complaint, the Texas law contains no exceptions for pregnancies that result from rape, sexual abuse, incest or for pregnancies involving a foetal defect incompatible with life after birth.