The United States and European Union are making headway on a free trade pact, but the two sides remain at odds over U.S. exports of beef and chicken that fail to meet tough EU safety standards, negotiators said on Friday.

After a fifth round of talks between the world's two biggest economic regions, negotiators for both sides said they made steady progress on common standards and regulations in many areas.

The talks are expected to intensify in coming months and U.S. Trade Representative Michael Froman said they had now moved from discussing a conceptual framework to defining specific ideas for addressing the majority of trade issues.

But there was no sign of resolving a standoff over farm exports in the Transatlantic Trade and Investment Partnership (TTIP), which would account for a third of global trade and almost half the world economy.

The European Union is closed to U.S. beef from cattle raised with growth hormones and to chlorine-washed chicken, which consumers fear make the food unsafe.

Chief U.S. negotiator Dan Mullaney said the United States was still pursuing increased market access for beef and there were "deep conversations" about the basis for food safety rules.

"The United States has no intention of forcing Europeans to eat anything a European does not want to eat. That's not what this agreement is about," he told reporters. "But it is significantly about providing protections on food safety for our populations."

Difficulties over agriculture are a worrying sign because negotiators are seeking a sophisticated agreement going beyond farm goods to bring down barriers and harmonize regulation across industries.

The United States sees EU food safety rules as veiled protectionism for European farmers and insists any restrictions be based on scientific evidence. But the EU's lead negotiator, Ignacio Garcia-Bercero, said the European team had made it clear food safety laws will not become less restrictive.

"Hormone-treated beef is prohibited under European Union law and certainly we do not envisage any changes," he said.

In a recent trade deal with the European Union, Canada won the right to export more hormone-free beef to the EU, but U.S. farmers say setting up separate processing chains for hormone-free products would be too costly.

Talks are still ongoing over separate TTIP sections on energy and financial services, which the EU is pushing for but the United States resists, negotiators said. The goal is to finalize the pact by the end of 2015.