The commissioners turned down the request from the Central Science Laboratory, the main research arm of the Ministry of Agriculture, Fisheries and Food, to lease an area of church-owned land near its York headquarters.

Scientists told the commissioners that the land would be used for scientific trials, which was understood to mean the possible planting of GM crops.

But the commissioners said the church would not lease the land until after an inquiry into the "theological implications" of genetic modification.

Lengthy inquiry

The block came after the church's Ethical Investment Working Group, charged with examining the GM issue, concluded it needed a "a period of further deliberation and reflection".

The Rev Cawthorne: "There has been concern that the GM process has been developed too speedily"

The group will look into all the ethical and theological aspects of genetic modification, including the technology itself, its possible effect on famers in the developing world and what it means for current theology. The inquiry is expected to take several months.

"The group is conscious that it is more important to come to a right view than a hasty one," a spokesman told BBC News Online.

"It's an extremely complex issue."

He added that the church was "aware of the issues and not afraid to confront them".

'More information needed'

The Rev Paul Cawthorne, a Telford vicar campaigning for further GM research by the Church, welcomed the decision.

GM crops: "Complex theological issues" says Church

"I'm not pressing the church not to go ahead," he told BBC Radio 4's Today programme.

"I'm calling for greater public consultation and reflection from within the Church to understand what ethical issues are involved before making any decision."

He said that debate had started within the Church but that it also required more information about the tests, including details of processes and timescales.

"There has been a concern that this process has been developed too speedily for us to understand the full implications of it," he said.

The Church of England owns more than 123,000 acres of agricultural land in the UK, said to be worth £237m.

Trials of GM crops have proved to be controversial and sites have been targeted by protesters.

Christian Aid raised concerns about the effects of the technology on farmers in the developing world.