United Nations Secretary-General Antonio Guterres has flown to Egypt’s Sinai Peninsula on Friday in a push to get aid flowing into Gaza, but it was unclear when delivery of relief materials stockpiled in Egypt would start.

According to Reuters, the United States said details of a deal to send aid through the Rafah crossing between Sinai and Gaza were still being hammered out.

UN officials say that any delivery of aid needs to be done at scale and in a sustained way. Rafah is the only crossing with Gaza for goods and people that does not border Israel.

Roads leading into Gaza are being repaired after being hit by bombardments in the past two weeks. A UN official said more than 200 trucks of aid were ready to move from Sinai to Gaza.