President Boris Yeltsin has ordered tighter restrictions on the country's wild young securities markets to protect inexperienced investors, his office said Wednesday. Under a decree signed Saturday, issuers of stocks and bonds will have to register them with the government and submit to tight regulation if they want to offer their securities to the public. Issuers' capital must be fully paid up before the issues will be registered. Publicly held companies also will have to provide quarterly balance sheets and profit-and-loss statements.In the credit markets, the decree requires companies offering short-term deposit certificates to obtain government licenses and bars issuers from offering longer-term unsecured debt securities unless they have been in operation for three years or more.