The board of directors of a public limited company can issue the shares provided that the company has enough unissued capital. The company can issue the shares up to the amount of authorized share capital. This amount is stated in the memorandum of the association of company. If the company has issued all the nominal capital then it can raise more capital by issuing shares. A public limited company issues share according to the company's articles of association. The amount of increased capital is announced in the members' general meeting. In some cases the shares can be issued at premium, depending upon the market value of the shares. For complete details regarding the legal procedure click on the link:
Issuing shares by Public Limited Company
Issuing shares by Public Limited Company