PYONGYANG, Apr. 19 (Reuters) - The U.S. ambassador to the United Nations said on Friday that she hoped to find a new way to ensure sanctions enforcement on North Korea by next month after Russia and China thwarted the renewal of monitoring activities.

Linda Thomas-Greenfield said Washington and its allies were looking at multiple options both inside and outside the UN to replace a panel of experts that has over the past 15 years monitored the implementation of sanctions aimed at curbing North Korea's nuclear and missile programs.

Russia rejected the annual renewal of the panel last month, while China abstained from the vote.

Asked whether the United States and its allies could establish an alternative by the time the current panel's mandate expires at the end of April, Thomas-Greenfield said:

"That would be the optimal thing to start next month. I don't know that we will move it that fast. But that's my hope," she told reporters in Tokyo.

"We're working to do something in the (UN) General Assembly. We are pushing the (UN) Secretariat through the Secretary General to do something out of his office, but we are also looking at options outside of the UN," she said, adding that those could be under the auspices of the G7, or with think tanks or research entities.

Thomas-Greenfield said the United States and its partners who are pushing for a new monitoring regime may look at having several teams replace the work of the existing panel.

"There may be not just one option. It may be looking at two or three different options that will get us the information that we need," she said.

Photo from Reuters