Mexico blocks caravan of 1,200 Central American migrants

An asylum seeker in Tijuana, Baja California state, Mexico, rests while waiting his turn to present himself to US border authorities and request asylum. (AFP/Guillermo Arias)

Soldiers and police forced the large group of migrants - who were mostly from Honduras - to a halt in the southern town of Metapa de Dominguez, about 12km from Mexico's border with Guatemala.

Migrant rights activists traveling with the group told AFP more than 100 members of Mexico's newly created National Guard took part in the operation, which was led by the government's National Migration Institute (INM).

Tension flared as officers brandishing anti-riot shields blocked the migrants' path, the activists said. But despite a shoving match, the authorities managed to force the caravan to a stop.

Several migrants were detained. The authorities did not immediately say how many, or what they planned to do next with the caravan.

Separately, migrant rights group People Without Borders (Pueblo Sin Fronteras) said two of its members had also been detained: Its leader, Irineo Mujica, in the northern state of Sonora, and another activist, Cristobal Sanchez, in Mexico City.

Authorities did not initially deter the caravan when they crossed the bridge over the Suchiate river, which forms the border between Guatemala and Ciudad Hidalgo, Mexico.

Mexico has deployed the National Guard to the southern border and stepped up detentions and deportations in a bid to slow the flow of migrants crossing its territory toward the United States.

But migrant detentions at the US-Mexican border still increased by 32 per cent month-on-month in May, to more than 144,000, according to US Customs and Border Protection.

The surge of migrants crossing Mexico toward the United States in recent months has provoked Trump's wrath. Last week he threatened to apply tariffs of five percent on all Mexican exports starting Monday, and rising incrementally to 25 per cent by October.

A high-level delegation led by Mexican Foreign Minister Marcelo Ebrard is currently in Washington in talks to try to avoid the tariffs.

The migrants are mainly Central Americans fleeing poverty and violence, often traveling in families - and sometimes in large caravans seeking safety in numbers.