Malcolm Turnbull has said the cross-party marriage equality bill produced by Dean Smith is a good starting point for parliament, as lawyers and Liberal MP Warren Entsch blasted a rival conservative bill that allows wide-ranging discrimination against same-sex weddings.

Entsch told Guardian Australia he was “surprised and disappointed” that the Liberal senator James Paterson had put his name to the bill, released on Monday, which accedes to conservative demands to allow private service providers to reject same-sex weddings.

The Law Council of Australia president, Fiona McLeod, said the Paterson bill encroached on anti-discrimination laws amended in 2013 to protect LGBTI people “in an extraordinary and perilous way”.

Paterson has conceded the bill allows differential treatment of same-sex couples, but said it did not give “carte blanche” for discrimination because only wedding-related services could be refused.

At a media conference in Manila, where he is attending the East Asia summit, Turnbull said in the event of a yes vote in the same-sex marriage survey, Coalition members would have a free vote, and senators would determine which bill to deal with first.

Asked about Smith’s bill, Turnbull said it had “been around for some months and is clearly a good bill to start with”.

“In a situation like this when a bill is presented, it’s like the first draft, so that gets put up, and there’ll no doubt be plenty of amendments ... debated, no doubt, for hours on end and at the end of it they’ll come to a conclusion on an amended bill.” Read more via the Guardian