The crisis in Turkey, which saw the lira currency tumble over five percent on Thursday, and a similar fall in Argentina's peso are having a negative knock-on impact on emerging markets, an economist said on Friday.

The lira's sharp retreat followed a report that Turkey's central bank's deputy governor was set to resign, while the peso plumbed a record low after Argentinian President Mauricio Macri announced he had asked the International Monetary Fund to speed up payments from a $50-billion credit line.

Jameel Ahmad, global head of currency strategy and market research firm FXTM, said emerging market currencies were feeling the pain on Friday as a result.

"The emerging market sentiment is being walloped once again from the signs of another currency crisis in Turkey escalating, with the South African rand once again being caught in the crossfires of investor reluctance to take the risk on higher-yielding assets," Ahmad said.

"The fear that the Turkish lira might be on the verge of crashing to another all-time low against the dollar is something that will present a risk to a negative knock-on effect for the rand. The situation for Turkey really does not look promising (and) the number of different challenges staring directly at the Turkish economy are at risk of becoming too long to list."

The currencies of countries saddled with wide current account deficits, such as the rand, India's rupee and the Indonesian rupiah, were among the hardest hit.

Earlier this month, the rand fell as much as eight percent to its weakest level in more than two years against the US dollar, breaching the 15.00 mark, again impacted by the turmoil in Turkey.

Ahmad said the decision by rating agency Moody's to downgrade the credit rating of 20 Turkish financial institutions had highlighted the fragile the financial system in that country.

A high proportion of debt in Turkey is denominated in either dollars or euros. Ahmad said speculation was expected to rise over the possibility of borrowers defaulting on their debt, as the lira has weakened as much as 80 percent so far this year.

He said while Turkey had long been considered as a high-yielding emerging market for investors, its problems were now so deep that it was very possible that investors would stay clear from other emerging markets over fears of contagion.

"This warning from Moody's has simply added to a cocktail of different concerns over the Turkish economy that also includes a number of prolonged structural challenges that remain unchanged," he said.