Conrad Cafritz, the financially troubled Washington real estate investor, has taken an important step toward resolving his financial difficulties outside of bankruptcy court by reaching an agreement with his largest creditor.

Sources said Helsinki-based Skopbank, which had lent Cafritz $87.8 million, has given Cafritz more time to pay back his loans and has committed to lend him an additional $110 million over a period of several years, mainly to build warehouses in Anne Arundel County.

Cafritz, 51, owes more than $1 billion but has fallen behind on loan payments and has asked most of his 71 lenders to renegotiate payment terms without forcing him into bankruptcy.

Participants in the Cafritz negotiations said the Skopbank agreement, which Cafritz confirmed yesterday, was an encouraging sign. Sources said the complex agreement could generate millions of dollars over time to help repay some of Cafritz's other creditors.

"It seems like it is very positive," said one of Cafritz's other bankers, who declined to be identified. "It's certainly a move in the right direction."

Cafritz is asking lenders to give him at least through 1993 to sell or refinance his holdings.

If he were forced to sell his real estate this year at fire-sale prices, creditors would end up with a shortfall of slightly more than $120 million, according to the Cafritz proposal. If Cafritz is given until 1993, he estimates a shortfall of less than $15 million.

The Cafritz projection assumes that conditions for selling real estate will improve over the next three years.

Skopbank officials in New York declined to comment on the bank's agreement with Cafritz. In return for giving Cafritz more time to repay his loans, the Finnish bank received a larger ownership stake in the projects it is funding.

"They think the projects they're investing in are excellent projects with very significant profit potential," Cafritz said.

Skopbank committed to fund construction of two warehouse and office projects in Odenton, Md., near Fort Meade.

The Finnish bank also extended loans on other Cafritz land holdings in Maryland and Virginia, including the Freestate Raceway site north of Laurel, which he bought for a reported $17 million last year, and a development site near Dulles International Airport.

As part of the deal, Skopbank released Cafritz from his personal guarantees to back some of his original borrowings from the bank. "Obviously, under the circumstances, the guarantees don't have very much value," Cafritz said.

According to American Banker, a banking industry publication, Skopbank is the world's 316th-largest bank. The second-largest bank in Finland, it works with funds pooled from other Finnish financial institutions. Cafritz is one of its principal American borrowers.

Like many other real estate companies, Cafritz's sprawling business began to founder early this year.

He had been counting on the ability to make profitable leases, sell properties and replace expiring loans with new ones. But each of those tasks became more difficult amid an oversupply of new development, higher than anticipated interest rates, a retrenchment on the part of foreign investors and a general tightening of real estate lending.

Cafritz has interests in about 100 to 120 properties, including shopping malls, apartment houses, undeveloped land, warehouses and office buildings in the Washington area and other parts of the country.

Even as he negotiates with his lenders, Cafritz continues to develop new properties and sell and refinance other real estate. Cafritz has already completed or is close to completing sales this year of properties that were mortgaged for $195 million. Those transactions are expected to generate cash to cover about 97 percent of that debt, plus another $5 million for other creditors, according to Cafritz's report to creditors.

Bankers and lawyers said that forging a consensus among the many creditors to avoid a costly, protracted bankruptcy proceeding is a delicate task.

If some of the lenders choose not to go along with a coordinated solution to Cafritz's financial difficulties, they could jeopardize the entire effort.

Sources said Cafritz's lenders generally seem inclined to negotiate a solution outside of bankruptcy court, but some object to elements of his repayment plan and many are still deciding what to do.