The D.C. statehood convention last night tentatively approved expropriation by the state of private utilities, and establishment of an economic development bank under a proposed constitution for the proposed new state.

The convention, finishing up an "economic development" article of the constitution, earlier had adopted language that would permit government employes -- including police, fire and hospital personnel -- to strike, except in certain limited circumstances.

The article has stirred heated debate, pitting left, right and centrist factions of the 45-member convention against one another over the degree to which the new state should control the local economy.

Several delegates also expressed concern that the novel and unusual language in the article may not sit well with Congress.

"We have added controversy which I believe puts the constitution in jeopardy," said Ward 2 delegate Wesley Long, pushing for a simple 56-word "general welfare" provision to replace the 15-page economic development article.

Ward 8 delegate James Coates retorted that the 15-page article would help assure that the city's business establishment and "high-paid lawyers" do not "rape, rob and prostitute our citizens . . . "

"Why should I trade my present bondage without statehood for another" form of bondage by writing a constitution that lacks economic protection for ordinary citizens?" he asked.

The economic development language approved on first reading last night included provisions that would:

* Permit all public workers to strike except when an unspecified "compelling governmental interest" justifies stopping a strike. U.S. workers are barred by law from striking.

* Authorize the new state to acquire private utilities by eminent domain. States generally have that authority now, but it is rarely specified in state constitutions.

* Require the state to establish a "comprehensive land use plan" with a 40-member citizen advisory commission appointed by the governor to help formulate the plan.

* Create a state economic development bank as a bank "of last resort" for businesses unable to obtain conventional private loans.

In another development yesterday, 18 of the 20 members of a D.C. Statehood Commission were sworn in by D.C. Superior Court Judge Luke Moore to be the official promoters of the city's bid for statehood.

The commission, which includes Mayor Marion Barry, D.C. congressional Del. Walter E. Fauntroy and other city leaders, will present the constitution first to the city voters and later to Congress.

The convention has until May 29 to finish writing the document.