Leaders of Maryland's public university system sent a letter to all 130,000 students yesterday warning that a worsening state budget deficit may force them to raise tuition for the semester that starts in a few weeks.

Campus officials said the "extraordinary" last-minute move could entail increases of up to 5 percent to make up for midyear budget cuts they expect will come from state lawmakers in the next several weeks.

No formal decision to raise tuition has been made, the officials emphasized, because no such cuts have yet been ordered, and the size of any increase could vary among the system's 11 degree-granting campuses. But Chancellor William E. Kirwan said the system's own analysis of Maryland's economic picture has led him to conclude that another round of deep cuts -- on top of $42.5 million already cut from the higher education budget this year -- is inevitable.

"We're caught in a time warp here," Kirwan said. "On the one hand . . . significant cuts are possible, but we don't know that for certain. On the other hand, we feel a moral obligation to alert students that this could happen."

Legislative leaders yesterday confirmed Kirwan's fears. Maryland Gov.-elect Robert L. Ehrlich Jr. (R) is expected to propose slowing state spending by hundreds of millions of dollars when he releases his first budget next week, rejecting pay raises for state employees, slashing thousands of vacant state jobs and cutting spending on higher education.

According to lawmakers who received budget briefings from Ehrlich aides over the past week, the budget is also expected to include more than $500 million in new funds, including proceeds from the legalization of slot machines and transfers from the state's primary road-building account.

In an interview with the Associated Press, Ehrlich said he believes that a five-cent increase in the gasoline tax will be needed during his first term to maintain state roads. But he is not expected to propose a gas tax increase in his first budget, sources said.

Ehrlich spokesman Shareese N. DeLeaver would not comment on the budget plan. Ehrlich must plug a $1.2 billion gap between projected revenue and state spending for the fiscal year that begins in July.

At the University of Maryland, whose College Park campus has nearly 35,000 undergraduate and graduate students, officials said a 5 percent tuition increase would amount to $114 for in-state students -- bringing the spring semester's tuition to $2,394, not including room, board and fees -- and $333 for non-Marylanders, for a total of $6,993. At Salisbury University, a smaller public college on the Eastern Shore, a 5 percent increase would mean about $85 for in-state students.

The letter to students comes as state officials grapple with a deficit of more than $500 million for the current fiscal year as well as a projected shortfall of $1.2 billion for next year's budget. Last week, outgoing Gov. Parris N. Glendening (D) proposed cuts totaling about $175 million. Critics said that would fall far short of solving this year's fiscal problems.

After several prosperous years, the university system absorbed deep cuts at the start of this academic year, including a round of midyear cuts last fall. Last spring, the Board of Regents raised tuition at most campuses by 5.5 percent -- dropping its longtime limit of 4 percent -- and imposed a hiring freeze and spending cuts throughout the system.

Facing a similar budget crisis, most Virginia public colleges announced midyear tuition increases last fall. But while Maryland officials have warned for months that steeper tuition increases may be in store for next fall, there had been little talk of a midyear price hike until now.

Some campuses have already mailed out bills for the spring semester. At the University of Maryland, campus officials said they were hoping a decision about increases could be made by next week, in time to amend the bills they have yet to send. But system officials said it is more likely that campuses would apply any increase to a separate bill midway through the semester.

System leaders acknowledged that a last-minute increase would probably irritate many students and parents but noted that it is not unprecedented. In early 1991, during the state's last severe recession, campuses raised tuition just before the start of spring semester.

Other state universities are having to make similar choices in the current economic climate, said Travis Reindl, a policy analyst with the American Association of State Colleges and Universities.

"The budget situations change day by day, and they don't want to raise tuition until or unless they really have to," he said. "It's viewed as a last-resort situation, and often you don't know you're in a last-resort situation until the numbers are really in front of you."

Kirwan said that if more state cuts are ordered, a tuition increase would be the only way to avoid major layoffs, which would "compromise the quality of the education and the services we offer."

"We feel a moral obligation to alert students that this could happen," Chancellor William E. Kirwan said.