Millions of people awaiting US travel documents have been left in limbo, as a major computer glitch crashed the United States global system for passport and visa services.

US State Department Spokeswoman, Marie Harf, says the glitch, which was first discovered on 19 July, has stalled the issuance of US passports and visas.

The State Department is working with utmost urgency to correct the "significant performance issues" with its Consular Consolidated Database and hopes to have the services resumed soon, said Harf.

It is not immediately clear how many have been affected globally but one official estimated that approximately 50,000 applicants were hit in one country alone, according to AP.