"Rahulji has gone to South Korea on an official tour," a Congress source told IANS.

The former party chief left for South Korea on Monday morning, the source said, but did not reveal for how long Rahul Gandhi would be away.

Meanwhile, Priyanka Gandhi, in the absence of her brother, took the lead in Congress protests. At the India Gate protest, she was joined by several senior party leaders like Ahmed Patel, K.C. Venugopal, Ghulam Nabi Azad, Ambika Soni and others.

But despite her dharna, many party activists questioned the absence of Rahul Gandhi.

On Twitter, Rahul Gandhi's former aide Pankaj Shankar wrote: "Hope he is not abroad", and in another tweet, he asked where Rahul Gandhi was.

In the past too, on several occasions, Rahul Gandhi has been criticised for being missing in action when significant developments were unfolding in India. On some occasions it later emerged that he had gone abroad in such instances.

When IANS contacted Rahul Gandhi's office for details, his staff responded with a "Why are you asking?" and denied any knowledge about his whereabouts. "Please send a mail to Rahul Gandhi's official mail id" was the response. Immediately after the CAA became law, Rahul Gandhi had raised serious objections to it. He had last courted controversy on Saturday when he drawn the ire of new ally Shiv Sena for his "I'm not Rahul Savarkar, and I am Rahul Gandhi and I won't apologise for speaking truth" remarks.

Protests, accompanied by violence in some instances, have broken out in Delhi and many other parts of the country after the Citizenship Amendment Bill became a law.