The Trans-Pacific Partnership trade negotiations remain stalled over five topics — including the key issue of market access and tariff elimination, sources said.

One market-access proposal under discussion calls for all parties to agree on the removal of tariffs on all products before moratoriums are set up on the removal of tariffs for certain products of special concern to TPP participants, they said Tuesday.

One of the sources said it was likely that some of the decisions would be subjected to political decisions in the final phase.

The other four problematic issues are intellectual property rights, environmental problems, labor and electronic commerce, the sources said.

The 11 TPP negotiation participants, including the United States, Australia and Malaysia, hope to reach broad agreement on the free-trade deal by October and sign the pact by year's end.

But the stalemate over the five topics and Japan's imminent participation in the talks are expected to make it difficult for the negotiating parties to meet the schedule, the sources said.

Negotiations have ended on five of the 29 planned chapters — trade facilitation, standard unification, telecommunications, development, small and medium-size enterprises — and have effectively been completed on nine others, one of the sources said.