The federal government, a city government, a UN human rights group and business and activist groups are weighing in on the newly enacted Texas abortion law informally known as the "heartbeat bill", which effectively bans almost all abortions after six weeks, including in cases of rape and incest.

Republican Texas Governor Greg Abbott on Tuesday defended the bill, saying  it allows rape victims up to six weeks to get an abortion, arguing that it "does not do that (force victims to have their assaulter's child)," the local NBC television affiliate, KXAN, reported. He said that the state will work toward eradicating all rapists.

On Monday, US Attorney General Merrick Garland pledged to protect abortion clinics in Texas by enforcing the FACE Act, which stands for Freedom of Access to Clinic Entrances Act and was signed into law in 1944. 

The law "prohibits the use or threat of force and physical obstruction that injures, intimidates, or interferes with a person seeking to obtain or provide reproductive health services," Garland said in a statement.

"The department will provide support from federal law enforcement when an abortion clinic or reproductive health center is under attack," Garland said. "We will not tolerate violence against those seeking to obtain or provide reproductive health services, physical obstruction or property damage in violation of the FACE Act."

President Joe Biden called the abortion law "almost un-American" and vowed a "whole-of-government effort" to fight it.

Courts have blocked other states from imposing similar restrictions, but Texas' law differs significantly because it leaves enforcement up to private citizens through lawsuits instead of criminal prosecutions.

The US Supreme Court last week declined to block the law in a 5-4 vote that has provoked outrage from liberals and cheers from many conservatives.

While small rallies were held across the country last weekend to protest the law, the Women's March said it is working with more than 90 organizations to mobilize a nationwide rally on Oct 2 against the law.

Republican officials in at least seven states, including Arkansas, Florida, South Carolina and South Dakota have suggested they may review or amend their states' laws to mimic Texas' legislation, according to The Washington Post.

The city council of Portland, Oregon, will vote Wednesday on a resolution that would ban the purchase of goods and services from Texas in response to the law, Mayor Ted Wheeler's office said. The resolution also would bar state-employee business travel to the state until Texas either withdraws the abortion law or it is overturned in court.

"The Portland City Council stands unified in its belief that all people should have the right to choose if and when they carry a pregnancy and that the decisions they make are complex, difficult, and unique to their circumstances," according to a statement from the mayor's office.

Melissa Upreti, chair of the United Nations' working group on discrimination against women and girls, criticized the law as "structural sex and gender-based discrimination at its worst".