U.S. Special Climate Envoy John Kerry has tested positive for COVID-19 at the COP27 climate summit in Egypt, but continues to work by phone, the State Department said on Friday.

"He is fully vaccinated and boosted and experiencing mild symptoms. He is working with his negotiations team and foreign counterparts by phone to ensure a successful outcome of COP27," State Department spokesperson Whitney Smith said in an emailed statement.

Kerry has been leading U.S. efforts to clinch at deal at the two-week summit in Sharm el-Sheikh and has held multiple bilateral meetings at the conference, including with his Chinese counterpart Xie Zhenhua on Thursday.

Kerry's voice was noticeable hoarse during speaking appearances on Thursday.