WASHINGTON (REUTERS) - President Donald Trump threatened on Thursday (April 4) to put tariffs on cars coming from Mexico into the United States if Mexico does not continue to help Washington deal with the immigration and drug situation along the southern US border.

Trump told reporters at the White House he would put tariffs on cars or close the border, but he said he may start with the tariffs.

He also said he would give Mexico a year to try to stop the flow of drugs before putting tariffs in place.

"A lot of good things are happening with Mexico. Mexico understands that we're going to close the border, or I'm going to tariff the cars," Trump told reporters at the White House.

Trump said he would "probably start off with the tariffs - that will be a very powerful incentive."

Trump warned last Friday that he would close the US border with Mexico this week unless Mexico took action to help stop the flow of illegal migrants across the frontier.

Trump said on Thursday that media coverage in recent days has prompted Mexico to make moves to curb the flow of immigrants to the United States and take other action to ease the pressure on US ports of entry.

Separately, Mexican exporters said this week they were looking into sending their goods to the United States by air freight to avoid a five-mile-long line of trucks at the border caused by the Trump administration moving federal agents away from customs checks to immigration duties.

Auto parts and medical equipment makers were among the Mexican companies considering the more expensive air cargo to avoid incurring penalties for late delivery to US clients or factory closures, Luis Aguirre, the president of Mexico's manufacturing industry chamber INDEX, said late on Wednesday.