The market regulator Sebi has not given its approval yet. The open offer for shares in Amtek India made by group firm Amtek Auto will not begin on July 23,as stated earlier,D&A Financial Services,manager to the offer,said in a filing to the BSE. The firm had submitted the draft letter of offer to the market regulator Securities and Exchange Board of India,who is yet to make its final observations on the offer. The revised schedule will be announced after it receives the final observation letter from SEBI,the statement said.