Secretary of State John Kerry said Wednesday he hopes to secure a "pause" in the Yemen conflict as he announced $68 million in new U.S. aid for the struggling nation.

A coalition led by Saudi Arabia, a key ally of Washington, has been bombing Yemen for six weeks to stem a spiraling crisis sparked by Iran-backed Shiite Houthi rebels' play for power.

Kerry — who arrived in Yemen's neighbor, Djibouti, on Wednesday — said he was in discussions with the Saudi government about a "pause" in the violence so that humanitarian aid could be delivered.

He said a pause would be "welcome news for the world" if it could be achieved without "people trying to take advantage of it," referring to a previous unsuccessful attempt at a temporary ceasefire.

"We are deeply concerned about the humanitarian situation that is unfolding in Yemen," Kerry said after announcing the new aid package. "Shortness of food, shortness of fuel, medicine…the situation is getting more dire by the day."

He said the $68 million would help humanitarian organizations meet the needs of 16 million people affected by the conflict, some 300,000 of whom have been forced to flee their homes.

The boost is more than two-and-a-half times the $26 million given by the U.S. to help the Nepal earthquake relief effort. It brings the total assistance provided by Washington to Yemen through fiscal years 2014 and 2015 to more than $188 million, according to the State Department.

Kerry spoke at Djibouti's Camp Lemonnier, the only U.S. base in Africa, and met American citizens who had fled there from the conflict in Yemen.

At least 646 civilians have been killed and 1,300 others injured since the coalition airstrikes began in late March, the United Nations said Tuesday, adding that the violence has caused "severe destruction of civilian infrastructure."