The Charities Property Fund is to limit new investment because of a shortage of suitable new properties to buy.
The common investment fund, which has grown rapidly since its launch in 2000 to reach a value of £215m under management, is to set up a waiting list for charities that wish to join.
All new applications will be date-stamped and some that had hoped to be accepted into the fund in December might have to wait until the next investment opportunity in March.
Charles Mesquita, charities specialist with the fund's owner, Carr Sheppards Crosthwaite, said managers had acted to safeguard returns to existing investors, who would be hit if too much new investment was permitted.
"We have taken soundings from a number of existing unit-holders as well as prospective investors and there has been general agreement that protecting existing investors' interests must be paramount," he said.
He explained that the demand for property was outstripping supply because of a "hot" property market. This meant that the fund had to be very selective about which properties it bought.
Fund managers did not want to allow surplus investment that would have to be temporarily held in lower-yielding cash deposits pending investment in property. "We don't want performance diluted," said Mesquita. "Normally we have around £2m deposited in cash, and we aim to be as fully invested as possible. Yield on property is 6 to 8 per cent and cash is 4 per cent. The more cash we have, the more drag there is on performance."