B. F. Saul Real Estate Investment Trust reported yesterday reduced losses for the first quarter of its new fiscal year while another trust, Bethesda-based Mortgage Investors of Washington, reported increased losses for the recent quarter and nine months ended Dec. 31.

The Saul REIT, largest in metropolitan Washington, said operating results of owned properties improved substantially in the quarter ended Dec. 31, resulting in a net loss of $1.7 million compared with a $2.5 million loss for the same period of 1976.

Not counting certain non-cash charges, the Saul Trust loss was reduced by 65 percent to $480,000 from $1.4 million. Cash flow before debt payments from equity investments rose 30 percent to $4.6 million.

Mortgage Investors posted a loss of $2.4 million in the recent quarter compared with a loss of $759,703 a year earlier. That brought losses for the first nine months to $2.5 million vs. a loss of $2.1 million.

In the last quarter, MIW increased its reserves for possible loan losses by $1.7 million, the result of an evaluation of anticipated revenues and expenses associated with the sale of condominiums in an unnamed, 224-unit project owned by the trust.

Overall, MIW now has $6.4 million set aside in reserves to cover potential loan losses.

Under terms of an agreement with lenders, requiring a net shareholders investment of $11.5 million (compared with $10.1 million on Dec. 31), MIW now is in default.

The trust said a reduction of the requirement to $9.5 million and a waiver of the default has been requested of the lenders.