MEXICO CITY (REUTERS) - Mexico has returned 15,000 migrants in the past month, a senior government official said on Tuesday (April 23), pointing to an uptick in deportations in the face of pressure from the US President Donald Trump to stem the flow of people north.

Speaking at a news conference, Tonatiuh Guillen, head of the National Migration Institute, did not say to which countries the 15,000 were returned, but most of the migrants moving through Mexico are from Guatemala, Honduras and El Salvador.

A third of migrants currently arriving in Mexico are minors, and there are also now more than 1,000 Cuban migrants in southern Mexico, Guillen told reporters.

Speaking alongside Guillen, Interior Minister Olga Sanchez said Mexico was not to blame for an "unprecedented" increase in the number of Central American migrants entering the country.

However, she noted Mexico had an obligation to control its southern border with Guatemala and that migrants entering the country must respect Mexican laws and register with authorities.

Following a surge in apprehensions of Central Americans trying to enter the United States, Trump last month threatened to close the US-Mexico border if the Mexican government did not stop illegal immigration right away.

The administration of President Andres Manuel Lopez Obrador has stepped up migrant detentions and tightened access to humanitarian visas, slowing the flow of caravans north and leaving hundreds of people stuck in the south.