MEXICO CITY - A Mexican airline is offering one-dollar flights to undocumented migrants wishing to return to Costa Rica, El Salvador and Guatemala as the country struggles to curb arrivals from Central America.

The Reuniting Families programme, announced by Volaris on Thursday, aims to "to assist in the repatriation of migrants," the airline said on its Twitter account.

The offer will run until June 30 and is open to Central Americans in an "irregular migration situation" who wish to depart from airports in Tijuana and Ciudad Juarez -- both close to the US border -- or Guadalajara and Mexico City.

Passengers must be willing to board "the next available seat" in order to take advantage of the ultra-cheap fare, which does not include taxes.

Mexico City's airport charges an airport use fee of $45 for international flights.

Adult migrants must identify themselves with their unique identity document and minors must show a passport or birth certificate.

A wave of Central American migrants has arrived in Mexico in recent months after the government of leftist Andres Manuel Lopez Obrador, who took office on December 1, declared that he would have a more flexible immigration policy.

However, the United States has registered record numbers of mostly Central American migrants crossing into the US illegaly, which has sent tensions soaring between the two countries.

Following a threat by US President Donald Trump to impose tariffs on Mexican imports, both governments reached an agreement and Mexico has reinforced surveillance along its southern border, as well stepped up the number of arrests and deportations of migrants.