Yemeni government forces and their Arab allies are massing north and south of the Houthi-held Red Sea port of Hudaydah despite United Nations and aid groups warnings that a military operation there would put millions of civilians at risk.
Hudaydah port and province is controlled by the Iran-aligned Houthis and has been the entry point for 70 percent of Yemen's food supplies as well as humanitarian aid.
The country has been torn by more than two years of civil war that pits the armed Houthi group against the government of President Abd-Rabbu Mansour Hadi, which is backed by a Saudi-led Arab alliance. More than 10,000 people have been killed in the conflict and hunger is widespread.
Local officials said that Hadi's government, building on recent gains that included capturing the coffee export hub of al-Mokha in February, has amassed two recently-trained brigades -- one in Midi about 230 km (140 miles) north of Hudaydah near the border with Saudi Arabia, and another outside al-Khoukha region, some 130 km (80 miles) south of the city.
Government forces will have to cross large areas of Houthi-held territory from both sides as the movement still controls the most populated areas in Western Yemen, including the capital Sanaa, and the regions surrounding the port city.
Mohsen Khasrof, a senior military official in President Abd Rabbu Mansour Hadi's Aden-based government, said it was only a matter of time for an attack on Hudaydah to start after the United Nations rejected coalition demands that it take steps to ensure that no weapons reach the Houthis through it.
"The political decision of liberating Hudaydah has been taken and military preparations have been completed, only the timing remains to be decided," he told Reuters by telephone.
"The continued military escalation in Yemen, specifically the militarization of large regions on its Western Coast and the associated increase of humanitarian access obstacles and population movement restrictions, are of grave concern to the humanitarian community," the Office of the Humanitarian Coordinator in Yemen said in a statement issued on Tuesday. The port is located in a densely populated urban center where thousands of people live.
"This is only resulting in more displacement, more institutional collapse, and more suffering," the statement highlighted.
More than two years of civil war have cut food deliveries by more than half and pushed the Arabian Peninsula's poorest country to the edge of famine. The United Nations says nearly 3.3 million people, including 2.1 million children, are acutely malnourished.
"The Yemen Humanitarian Country Team calls on all warring parties and on those with influence over the parties to ensure the continued functioning of Hudaydah Port," the statement said.