The Japanese Yen jumped against the Dollar on Monday as traders pointed to intervention by Japanese authorities to support the currency, which has been at its lowest levels in over 30 years.

The greenback plunged to a low of 154.40 Yen from a high earlier in the day of 160.245. According to banking sources, Japanese banks were seen to be selling Dollars for Yen.

At the time of writing, it was trading at 155.83 Yen, according to Reuters news agency reports.

For weeks, traders had been awaiting any signs of action from Tokyo to support a currency that has dropped 11% against the Dollar this year. 

Despite the central bank's historic move last month to exit from negative interest rates, the Yen still plummeted to its lowest levels in 34 years.

Currency traders have wagered that despite the change, Japanese rates will stay low for a while, in contrast to the relatively high US interest rates.

According to Masato Kanda, Japan's top currency diplomat, the developments within the currency market were "speculative, rapid and abnormal" and could not be disregarded.

"Today's move, if it represents intervention by the authorities, is unlikely to be a one-and-done move," stated Nicholas Chia, Asia macro strategist at Standard Chartered Bank in Singapore.

"We can likely expect more follow through from MOF if the Dollar/Yen pair travels to 160 again. In a sense, the 160-level represents the pain threshold, or new line in the sand for the authorities."

Last Friday the Yen had moved almost 3.5 Yen between 158.445 and 154.97 as traders expressed their disappointment after the Bank of Japan kept policy settings unchanged and provided few hints on reducing its Japanese government bond (JGB) purchases. 

Such a move could potentially support the Yen's value.

"Whether it is in effect intervention, we will only know later," commented Mahjabeen Zaman, head of foreign exchange research at ANZ in Sydney.

"In past interventions, we have seen that the immediate response of the Yen is it moves by a few Yen but then it trades back in line with fundamentals and I think the biggest driver for Dollar/Yen is the US-Japanese yield differentials."