Ukraine's bondholder must take into consideration the possibility of reducing the coupon and writing off the principal of the country's foreign debt, Sergio Trigo Paz, head of emerging-markets fixed income at BlackRock Inc., one of the largest holders of Ukrainian government debt, has said.

"Ukraine’s creditors should not rule out the possibility of cutting the size of the country’s debt pile, which would involve investors sustaining losses on their bondholdings," he told reporters in London, The Wall Street Journal wrote.

"That’s why we prefer to sit on the sidelines" in the negotiations, said Trigo Paz, noting that the creditor committee is taking a "different approach."

"We always want to be constructive with countries in these situations. Right now, being constructive is staying on the sidelines," he added.