In an interview published on Saturday in the Sabah newspaper, Erdogan said the plans were aimed at buttressing the family, and that Turkey must not always blindly imitate Europe.
"The family is a sacred institution for us. The stronger the family, the stronger the country. If the family is weakened, that country is doomed to destruction," said Erdogan, a pious Muslim whose party has roots in political Islam.
He vowed that any new law would respect privacy and would be applied only if either the wife or the husband lodged a formal complaint. No third party would be able to invoke the law.
"The West is not perfect. If we took it as a model of perfection in everything, we would have to deny ourselves and would perish"
Recep Tayyip Erdogan,
Turkish Prime Minister
Turkish newspapers and women's groups have criticised the plan, saying it pushes Turkey away from European norms and closer to the Islamic model of states such as Saudi Arabia, where adulterers are put to death.
On Saturday Turkish media quoted EU enlargement spokesman Jean-Christophe Filori in Brussels as saying the plan "could harm Turkey's image" and cast a shadow over its EU bid.
The European Commission is due to publish a progress report in October on Turkey's reforms that will form the basis of a decision in December by the 25 EU member states on whether to open long-delayed entry talks.
The plan is seen as a nod to the
ruling AKP's conservative base
"The West is not perfect," Erdogan said.
"If we took it as a model of perfection in everything, we would have to deny ourselves and would perish."
Turkish media have interpreted the plans as a nod by Erdogan's (AKP) towards its conservative and often religious electorate.
The bill would be part of an overhaul of the penal code, promised as part of reforms aimed at meeting EU criteria.
In the 1990s Turkey's top court struck down a law penalising adultery, saying it had been used mainly against women, leading to gender inequality.
Erdogan insists that any new law would actually boost equality between the sexes.
The EU is expected to complain of continued discrimination against women in Turkey in its October report.