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Matt Dunham, Associated Press
U.S. Secretary of State John Kerry, right, waves as he stands with Oman Foreign Minister Yusuf Bin Alawi bin Abdullah after arriving for their meeting at the official residence of the U.S. ambassador to Britain, Winfield House, in London, Tuesday, Nov. 18, 2014.

LONDON — U.S. Secretary of State John Kerry held an unexpected second meeting Wednesday in London with the foreign minister of Oman, which has emerged as a key go-between in nuclear talks with Iran.

A senior U.S. official said Kerry met Wednesday at his hotel with Youssef bin Alawi for follow-up discussion about the foreign minister's weekend trip to Tehran.

The talks come as negotiations with Iran in Vienna continue ahead of a Monday deadline for a nuclear deal.

Unlike their first meeting Tuesday, Wednesday's meeting was unannounced. It was confirmed only after an AP reporter saw the foreign minister in the hotel.

Oman, which has close ties with Iran, was the site of secret US-Iranian talks in March 2013. It hosted the last round of high-level talks earlier this month in Muscat.