The number of people receiving jobless benefits fell to the lowest level in 28 years, the Labor Department said Thursday, a further sign of a healthy labor market. Initial claims slipped 2,000 to a seasonally adjusted 236,000 for the week ended May 6, the Labor Department said on Thursday. Claims have now been below 300,000, a threshold associated with a healthy labor market, for 114 straight weeks. The four-week moving average of claims, considered a better measure of labor market trends as it irons out week-to-week volatility, rose 500 to 243,500 last week. The claims report also showed the number of people still receiving benefits after an initial week of aid fell 61,000 to 1.91 million in the week ended April 29. This is the lowest level of so-called continuing claims since November 1988. The four-week moving average of continuing claims fell 27,500 to 1.97 million. This is the lowest level for this average since February 1974. Federal Reserve officials believe the labor market is close to full employment, with the unemployment rate at 4.4 percent. With the jobless rate so low, Fed officials have said they need to raise interest rates gradually to protect the economy from overheating. The market expects the central bank to raise interest rates for the second time this year at its meeting in mid-June.