Shiv Shankar Menon is a busy man these days.

The unassuming diplomat and India's man in Beijing is playing a critical role in shaping India's two most important diplomatic moves in recent times, doing the groundwork for Prime Minister Atal Bihari Vajpayee's forthcoming visit to China and preparing to take over the high commissioner's post in Islamabad.

According to sources in the Ministry of External Affairs, Menon would take charge in Islamabad after the prime minister's trip to China.

He was in New Delhi recently after his appointment as high commissioner to Pakistan. After consultations, he returned to China, where the prime minister is expected in the last week of June.

Menon is expected to be back again some time next week in this connection. At that time, he would also hold consultations on Pakistan, officials said.

Prime Minister Vajpayee's visit is expected to give a major push to Sino-Indian relations. Apparently, there is a concerted effort on both sides to achieve some breakthroughs.

One of the key issues is China accepting Sikkim's accession to India.

Menon would be the prime minister's key adviser during his meetings with the new Chinese leadership, including President Hu Jintao.

Menon (54) is one of India's most experienced diplomats, having held several key positions in several foreign countries besides the MEA.

He was selected after the prime minister personally perused the various nominees to head the mission in Pakistan as part of efforts to find peace in the subcontinent.

Meanwhile, Pakistan's new envoy to India Aziz Ahmed Khan is expected to take charge in New Delhi by mid-June.