California is considering taking legal action against Donald Trump’s administration over the use of tear gas on migrants at the US-Mexico border.

“We have been approached by folks who have expressed complaints...We are monitoring what’s occurring.” California Attorney General Xavier Becerra told Reuters.

US border agents used the substance to disperse a crowd of mostly Central Americans, including children, trying to illegally entering the country at the San Ysidro port near San Diego, California.

The state has limited power over the federally-managed port but if a California resident was adversely affected by the tear gas use then they may have cause to take legal action.

“I can’t act unless the rules are on our side,” Mr Becerra said.

The tear gas incident prompted criticism of the administration, and particularly, Mr Trump's stance towards the migrant caravan of approximately 5,000 people camped out at a sports complex in Tijuana, Mexico.

Trump defends use of tear gas

Many are seeking asylum in the US as they are fleeing the rampant gang violence in their native Honduras, Guatemala, and El Salvador.

US border agents have been processing approximately 40 to 100 asylum applications a day at the San Ysidro port, leaving migrants with murky timelines on how long they will have to wait in Mexico.

The frustration came to a head on 25 November when hundreds of migrants attempted to storm the border barriers, apparently overwhelming the border patrol.

Tear gas and pepper spray were used and Trump administration officials have justified its use multiple times. Department of Homeland Security Secretary Kirstjen Nielsen called the incident "entirely predictable. This caravan, unlike previous caravans, had already entered Mexico violently and attacked border police in two other countries. I refuse to believe that anyone honestly maintains that attacking law enforcement with rocks and projectiles is acceptable."

Ms Nielsen also wrote that "90 per cent" of the migrants are not eligible for asylum in the US.

Per US Citizenship and Immigration Services, asylum seekers must "demonstrate [they] have suffered persecution or fear that they will suffer persecution due to" five factors: race, religion, nationality, membership in a particular social group, or political opinion.

Undocumented immigration across the US-Mexico border Show all 14 1 /14 Undocumented immigration across the US-Mexico border Undocumented immigration across the US-Mexico border Immigrant children, many of whom are separated form their parents, are housed in Texas' tent city Reuters Undocumented immigration across the US-Mexico border A two-year-old Honduran asylum seeker cries as her mother is searched and detained near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Undocumented migrants ride on the top of a freight train referred to as the beast, or La Bestia Getty Undocumented immigration across the US-Mexico border A cage inside a US Customs and Border Protection detention facility in Texas Reuters Undocumented immigration across the US-Mexico border US Border Patrol Academy All new agents must complete a months-long training course at the New Mexico facility before assuming their posts at Border Patrol stations, mostly along the US-Mexico border Getty Undocumented immigration across the US-Mexico border US-Mexico border fence A group of young men walk along the Mexican side of the US-Mexico border fence in a remote area of the Sonoran Desert Getty Undocumented immigration across the US-Mexico border US-Mexico border fence in the US Man looks through US-Mexico border fence into the US in Tijuana, Mexico Getty Undocumented immigration across the US-Mexico border US-Mexico border fence US Border Patrol agent Sal De Leon stands near a section of the US-Mexico border fence while stopping on patrol on in La Joya, Texas Getty Undocumented immigration across the US-Mexico border US Border Patrol Academy US Border Patrol instructor yells at trainees after their initial arrival to the academy Getty Undocumented immigration across the US-Mexico border Memorial service in Guatemala Families attend a memorial service for two boys who were kidnapped and killed in San Juan Sacatepequez, Guatemala. Crime drives emigration from Guatemala to the United States, as families seek refuge from the danger Getty Undocumented immigration across the US-Mexico border Arrests on the border Undocumented immigrants comfort each other after being caught by Border Patrol agents near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Detention holding facility A boy from Honduras watches a movie at a detention facility run by the US Border Patrol Getty Undocumented immigration across the US-Mexico border Mexican farm workers Mexican migrant workers harvest organic parsley at Grant Family Farms in Wellington, Colorado Getty Undocumented immigration across the US-Mexico border Mexican family in Arizona A Mexican immigrant family sits in the living room of their rented home in Tuscon, Arizona. The family that Arizona's new tough immigrant law had created a climate of fear in the immigrant community. Getty

Mr Trump himself has said the use of force was "very safe" and necessary in order to protect the border from the caravan, which he has called and "invasion" of "criminals" and accused of travelling with "unknown Middle Easterners" for several weeks.

He also demanded on Twitter Mexico should take more responsibility for the crisis. Following the incident he tweeted: "Mexico should move the flag waving Migrants, many of whom are stone cold criminals, back to their countries. Do it by plane, do it by bus, do it anyway you want, but they are NOT coming into the U.S.A. We will close the Border permanently if need be. Congress, fund the WALL!"

Support free-thinking journalism and attend Independent events

The United Nations and Democratic members of Congress have slammed the administration after photographs and reports of children fleeing the tear gas were published.

Some experts have cited language in the UN charter, which states members “shall refrain in their international relations from the threat or use of force against the territorial integrity” of other countries.

The Ninth Circuit federal district court in California had earlier blocked Mr Trump's executive order attempting to change US policies for seeking asylum. The administration is challenging the ruling and has floated the idea of giving migrant families who are seeking asylum 20 days to make the choice between staying in detention with their children until deportation hearing or letting their children be kept in a separate facility so relatives already in the US can come claim custody of them.