Military chaplains are busier than they have been since the second world war but the armed forces are struggling to recruit clergy because of a diminishing pool of priests, the Church of England's governing body will be told this week.

In a report to the General Synod, which opens tomorrow, chaplaincies from across the armed forces will highlight the discrepancy between staffing and demand.

The navy chaplaincy has dropped its minimum age requirement from 52 to 49 to attract more people. The RAF, which deployed 12 chaplains in 2009 to Afghanistan alone, says it has launched a recruitment campaign because of the shortages.

The Royal Army Chaplains' Department has experienced one of its busiest decades since the second world war, with more than 30 staff deployed simultaneously around the world on several occasions because of Britain's military operations. It has 27 people in Afghanistan and nine in Iraq.

One churchman said an absence of chaplains would be hamper operations. The Rev Stephen Sharkey was in Afghanistan with 4 Rifles, a mechanised infantry regiment that returned to the UK last October. It was his first deployment and he spent his four months travelling between Camp Bastion, Silab and Shawqat.

He said: "Around 20% of the battalion would never have been deployed before. There were new people coming in all the time. It is a young army. It has to be to survive.

"I let the soldiers know I was there, sometimes they would seek me out. We talked about everything ‑ pastoral, financial, personal, relationship, grief and bereavement issues. I would talk to anyone, whether they were Christian or not."

He said the majority of those he met were open to faith and spirituality. "Often they ask us to pray for them. They say it can't do any harm. When they go out they don't know if they will come back. When their friends go out, they don't know if they'll come back."

Addressing the hundreds of bishops, clergy and laity attending the synod will be the chaplain general of land forces, the Ven Stephen Robbins, the chaplain of the fleet, the Ven John Green, and the RAF chaplain-in-chief, the Ven Ray Pentland.

Other issues to be discussed during the five-day meeting are better pension rights for partners of gay clergy and religious content on television channels.

The synod opens tomorrow with the bishop of Manchester explaining why there has been a setback to draft legislation on the ordination of women as bishops. On Tuesday, the archbishop of Canterbury will deliver his presidential address. It is expected he will discuss ongoing debates in the Anglican communion about human sexuality and reflections on the apostolic constitution, a Vatican initiative to allow groups of Anglicans to convert to Catholicism.