US President Donald Trump has said he would not proceed with his stated plans to designate Mexican drug cartels as terror groups following a request from his counterpart Andres Manuel Lopez Obrador.

Mr Trump called for a "war" on the cartels last month after the killings of nine women and children from a US-Mexican Mormon community.

The case brought fresh attention to cartel violence in Mexico and President Lopez Obrador's struggles to rein in bloodshed, but south of the border the US plans were seen as unwanted meddling.

Mexican officials asked for clarification on Mr Trump's plans, and said they wanted to make progress on efforts to stem the flow of weapons and money from the United States to criminal gangs in Mexico.

Foreign Minister Marcelo Ebrard had reacted more forcefully, saying: "Mexico will never allow any action that means a violation of its national sovereignty."

While Mr Trump said in a tweet yesterday evening that "all necessary work has been completed" to declare Mexican Cartels terrorist organisations, but added that he was putting a hold on the move out of respect for Mr Lopez Obrador.

"We will temporarily hold off this designation and step up our joint efforts to deal decisively with these vicious and ever-growing organizations!" the president tweeted.

Mr Trump said Lopez Obrador was a "man who I like and respect, and has worked so well with us."

The Mexican president hailed the change of heart, telling reporters that joint action with Washington on cartels needed to be done "with respect for our sovereignty."

"I think the decision made today was very good," he added.

The victims in last month's attack, including twin eight-month-old babies, were killed as they drove on a remote road between the states of Sonora and Chihuahua, in northern Mexico, a lawless region disputed by warring drug cartels.