Maryland Gov. Harry Hughes announced today that he is calling the General Assembly into a special session Aug. 6 in an effort to offset federal cuts affecting thousands of jobless Marylanders.

Hughes said he is convening the "extraordinary session," the first since 1975, because nearly 11,000 unemployed workers are faced with the "terrible problem" of having their federal unemployment benefits cut off at the end of the month.

The affected workers are those who have been without jobs for more than 26 weeks. Previously, they would have qualified for an additional 13 weeks of benefits, but because of the way Reagan administration guidelines have been applied to Maryland, unless the state intervenes, they no longer will receive any compensation.

"Many of these people are having problems meeting utility bills, other necessities, mortgage payments," Hughes said. "It's become very serious at a time when you have high unemployment, when you need extended benefits."

Hughes, a Democrat running for reelection this fall, charged that the Reagan administration is ignoring human needs in its efforts to balance the federal budget. "This shouldn't be used as a bookkeeping gimmick," he said.

The decision to bring the state's 188 legislators back to Annapolis followed a meeting between Hughes and Maryland's congressional delegation on Capitol Hill. Delegation members told Hughes there is little hope that Congress will act swiftly, if at all, to restore the unemployment payments.

After the Washington meeting, Hughes spent several hours conferring by phone with state legislative leaders, who agreed that a special session was needed. Normally the legislature meets each winter for three months.

"There is general support for what the governor is doing," said House Speaker Benjamin L. Cardin (D-Baltimore). "This is a major problem worthy of a special session. We don't want to see these people lose their benefits and the only thing we can do is change the law."

Hughes said he will ask the legislature to make effective immediately legislation enacted earlier this year that allows the state government to pick up the cost of the federal cuts and continue paying unemployment benefits to the affected workers.

The legislation was scheduled to go into effect Sept. 26, when state officials had expected the federal reductions to occur. However, Maryland was hit with the cuts sooner because of a complicated twist in the federal formula.

Under the new formula, persons who have been out of work for more than 26 weeks no longer will be counted in unemployment statistics that the federal government uses to determine the amount of federal funds that each state is entitled to receive.

About a dozen states, including Illinois and North Carolina, are likely to lose federal money for extended unemployment benefits.

Hughes said that it will cost the state as much as $9 million to make up the cutback in federal funds. Previously, the federal government paid 50 percent of the extended benefits.

State officials said today that the benefit fund, which is the sole source of regular unemployment benefits, has about $275 million in reserve but is expected to run out by next summer. Hughes said that he would introduce or support legislation during the next session--presuming he is reelected--to bolster the trust fund.

Hughes said he decided to call the special session a week from Friday so that the 11,000 jobless workers will not miss any compensation. However, he added, the session could be delayed as much as a week if legislative leaders need more time to prepare for the one or two-day meeting.

Hughes will meet with state House and Senate leaders Tuesday to make the date final and to work out details for ensuring that the session does not get caught up in election-year wrangling. Unlike past special sessions--in the last 10 years three have been held--this session will occur at a time when all members of the state government are up for reelection.

"We do have people who are campaigning and we do have the possibility of a lot of posturing," said Hughes chief of staff Ejner Johnson. "We want to make sure we go in and do a nice surgical job and be done with it."

State Sen. Harry J. McGuirk, a member of the legislative leadership and Hughes' chief challenger in the Sept. 14 Democratic primary, said today he expects that most legislators will support Hughes and go along with a quick special session. "Everyone can see you're dealing with people who want to work and are caught in the Reagonomics of the time."

Hughes' call for a special session followed a demand for action by leaders of the state's politically active labor unions. The labor leaders, who have been watching the state's unemployment rate go as high as 10 percent, said they are withholding political endorsements until they can evaluate the actions of various candidates.

Several Democrats and Republicans contacted today said Hughes' decision in favor of a special session is likely to help him with organized labor.