More sanctions on Russia are likely to trigger a further sell-off in the ruble, according to one currency expert.

Russia's currency has already been faltering this week in the face of escalating tensions with the West in Syria, and more sanctions could be the trigger, said Simon Derrick, a chief currency strategist at BNP Mellon.

"What we have seen in the last week is the kind of price action that we've really only seen two or three times before over the course of the in last 20 or so years. Certainly in the late 2014 when we had the ruble crisis then, and before that in 1998 and a little bit round the global financial crisis in 2008," he told CNBC's "Capital Connection," highlighting that the recent moves in the ruble were reminiscent of other crises for the currency.

Over the last seven days, the ruble has fallen from 63 against the dollar to trade at 61.2, amid a war of words between Russia and the U.S. — and its allies — over Syria. More sanctions were expected to be imposed on Russia Monday, but the country appeared to win a reprieve with the White House stating that President Donald Trump had not yet approved additional measures.

"What you can say is that when you do see the ruble have a crisis, it usually works for two or three weeks and reaches a peak when you get, sometimes, moves of 10 percent or more in an individual day. And I think we're in that kind of cycle," Derrick added.

Traditionally, the Russian central bank has stepped in to support the currency by selling off amounts of its foreign currency reserves to buy up, and stabilize, the ruble on the international currency markets.