Tenants in an apartment building at 12-16 Ware St. yesterday filed a complaint with the city's Rent Control Board charging the owners of the building with attempting to convert it to a cooperative housing development without city approval.

Thirty-nine tenants signed the complaint, which will be reviewed by a rent board hearing examiner.

The tenants said Ware St. Associates told many residents of the building over the weekend that they can make a down payment on their apartments and begin paying mortgages instead of rent.

Tenants also said that although no evictions have been threatened, converting to a cooperative may be an attempt to remove the building from rent control protection. That would allow private investors to buy apartments and increase the rent of the present occupants.

A recent city statute requires developers seeking to convert their buildings to cooperatives--in which ownership of an apartment is equivalent to ownership of a share of the building--to obtain removal permits from the city's rent board.

Ware St. Associates partner David Zussman defended the decision to convert to cooperatives as "a unique offering" that would give "tenants and investors an opportunity of ownership."

Zussman said he does not know if rent control ordinances still govern units held by non-occupant investors.

Tenants will have until November 20 or 25 to decide whether to purchase their apartments, Zussman said.

The units are being offered to tenants at much less than their market value, Zussman said, adding that because of the low prices, many investors are interested in the properties.

"Our procedure is unique; we have no intention of removing tenants," Zussman said, adding that the group had not applied for a removal permit since it planned no evictions.

Tenants in the Ware St. building, located two blocks from the Yard, first received a hint of the conversion plans Friday, when Ware St. Associates member Emily Flynn left messages asking tenants to call her, Barbara Wishnov, who helped organize the tenant complaint, said yesterday.

Flynn told them they had until late November to decide whether to buy their units at prices around $30,000, tenants said.

Wishnov, who has lived in the building ten years, estimated that 85 per cent of the tenants are "people in their 70s and 80s" and added that she had "lost three nights' sleep worrying about the planned conversion."

Tenants met Sunday night to sign the complaint and seek advice from city tenant activists.

City councilor David Sullivan, who drafted the ordinance controlling cooperative conversion, said yesterday the attempted Ware St. conversion is the first since the legislation requiring removal permits to take apartments off the rental market passed in August 1979.

A rent board hearing examiner will make a recommendation on the case to the full board, Sullivan said, adding that if the board decided the developer was violating the ordinance it could seek either civil or criminal action.