The halt in construction on the Allston Science Complex late last year left plans for two of Harvard’s science schools to expand into the new campus in limbo, as school officials struggle to adjust to the now indefinite space constraints of the current campus.

Harvard Medical School and the Harvard School of Public Health both expected several departments to move into the new complex by the original 2011 completion date, but are now taking steps to accommodate growing programs by moving labs and leasing new property with little guidance from the University’s central administration.

“Our response is to rejigger all of our space to accommodate what was going to go into the first building [in Allston],” Medical School Dean Jeffrey S. Flier said in an interview last week. “Our departments are our departments, and we’re responsible for them.”

According to Flier, who also sits on the task force examining the University’s strategy going forward in Allston, there is little guidance the central administration can provide until a concrete long-term plan has been devised at the schools.

But University officials said yesterday they remain cognizant of the graduate schools’ expansion plans.

“The future space needs of our professional schools, as well as of the FAS, are part and parcel of our increasingly integrated capital planning process, which encompasses Cambridge, Allston, and Longwood,” wrote Executive Vice President Katherine N. Lapp in an e-mailed statement.

Flier said that the Medical School owns property where departments could move. But relocating departments to those buildings would require foregoing rent revenue from tenants who currently lease the space at a time the school is expected to make further cuts to its $560 million budget.

The groups affected at the Medical School include bioengineering researchers, stem cell scientists, and the department of systems biology—which currently has sufficient space but needs to relocate to allow for expected growth over the next decade.

According to Timothy Mitchison, deputy chair of systems biology, the department cannot accommodate any additional faculty members in its current building.

“We had an aggressive hiring plan,” Mitchison said, referring to the period before last year’s recession. “Most people have accepted that the growth of the department would slow a little bit. That takes pressure off the space.”

The School of Public Health faces a similar challenge—its current facilities are inadequate for its growing faculty and student body.

“We’re trying to decide what’s a responsible investment,” said David J. Hunter, the school’s dean for academic affairs, in an interview earlier this year.

But current efforts to make better use of the University’s property holdings have led some to question the original need for the Allston science building, especially as Harvard has already constructed two large laboratory buildings over the past decade—The New Research Building in Longwood and the Northwest Science Building in Cambridge.

“Looking back on Allston... the mentality seemed to be ‘if you build it, they will come,’ and maybe we’ve in some sense moved back to a more rational plan,” Mitchison said.

—Staff writer Elias J. Groll can be reached at egroll@fas.harvard.edu.

—Staff writer William N. White can be reached at wwhite@fas.harvard.edu.