Mexican authorities said on Friday that five attackers have died in a clash with soldiers in the northern border state of Tamaulipas, bringing the state's death toll in two days of presumed gang-related violence to 29.

A group of armed assailants attacked a military patrol Thursday on a highway near the Rio Grande, wounding one soldier, according to a Tamaulipas state official who was not authorised to be quoted by name.

The official said the patrol returned fire, killing five assailants.

Some of the gunmen were wearing bulletproof vests and military-style camouflage. The area where the confrontation occurred, near the town of Miguel Aleman, has long been dominated by the Zetas drug cartel.

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The town is about 80km west of McAllen, Texas, where US President Donald Trump visited Thursday to push for a border wall.

The state official said the death toll in a separate presumed drug cartel shoot-out on Wednesday near Miguel Aleman had risen to 24, with the discovery of three more bodies.

Experts originally counted 21 bodies, many found in twisted piles of charred corpses in a field near burned-out vehicles. But the state official said Thursday that continued investigations located three more bodies.

Those killings apparently arose from a dispute between the Gulf cartel and a faction of the Zetas cartel.