President Donald Trump has doubled US tariffs on Turkish steel and aluminium, as the precipitous fall of the Turkish lira accelerates.

In a tweet, Mr Trump said the currency was weak against "our very strong dollar", adding that "US relations with Turkey are not good at this time".

Turkish President Recep Tayyip Erdogan said in a speech that the drop was part of a "campaign" led by foreign powers.

Turkey also warned it would retaliate against the US tariffs move.

"The United States should know that the only result that such sanctions and pressure will bring... will be harming our relationship as allies," the Turkish foreign ministry said in a statement.

The two Nato members are at odds on a range of issues - how to fight the Islamic State group, Ankara's plans to buy Russian missile defence systems and how to punish the alleged plotters of a failed coup in Turkey in 2016.

Most recently, President Trump issued sanctions on top Turkish officials over the ongoing detention of a US pastor who is facing terror and espionage charges in Turkey.

In the past 24 hours, the lira has lost around 20% of its value. It had already fallen more than 40% in the past year.