A recent tweet by the Central Board of Indirect Taxes & Customs (CBIC), stated that,
As per the Goods and Services Tax (GST) law, a person registered as a composition taxpayer cannot issue a taxable invoice and can neither collect GST from his customers nor can claim the input tax credit on his purchases.
The fact as to whether a person is a regular taxpayer or a composition taxpayer can be verified on the GST portal under the "Search Taxpayer" -> "Search by GSTIN/PAN" tab under the heading "Taxpayer Type". The URL for the same is https://services.gst.gov.in/services/searchtp