BRUSSELS (Reuters) - Following are key elements and negotiating difficulties in a draft EU plan to have Turkey stem the flow of migrants to Greek islands in return for financial and political concessions:

1. RETURNS

Turkey to take back anyone who crosses to Greek islands from its coast without regular travel papers.

Problems:

- Greece needs to set up tribunals to hear asylum claims and appeals quickly.

- Turkey needs to amend legislation so that the EU can say it is a “safe third country” for refugees who are sent back. The United Nations and rights bodies are skeptical about the plan.

- Returns cannot start until Turkey agrees at least a basic level of protection to all nationalities returned to its soil. At present it only grants such protection to Syrians, but non-Syrians make up two-thirds of the migrants.

- The draft does not say when the scheme starts. Diplomats say Germany is keen for it to begin as soon as possible, so that people arriving on Greek islands as early as Monday could be held for expulsion back to Turkey. Greece says its services are not ready. EU officials fear delay may fuel a rush to cross the Aegean before any deadline.

2. RESETTLEMENT

For every Syrian refugee returned to Turkey, another Syrian refugee will be resettled from Turkey to the EU, with priority given to those who have not previously crossed to Greece.

Problems:

- EU states are divided on sharing out asylum seekers. They have outstanding voluntary offers to resettle only about 18,000.

- A further 54,000 places could be offered by tweaking a scheme intended to relocate people from one EU state to another. But eastern states oppose those obligatory quotas.

- If more than 72,000 places are needed, there would be more arguments about who would provide them. But officials say if that number of Syrians are still reaching Greece, the entire scheme, intended as a deterrent, may be considered a failure.

3. ALTERNATIVE ROUTES

Turkey to work with EU to bar other routes.

Problems:

- Bulgaria is especially concerned about its Turkish border.

- There are signs more people may try to sail to Italy.

4. LONGER TERM RESETTLEMENT

In the longer run, once EU states are satisfied that Turkey has really stopped the flow of migrants across the Aegean, the EU is offering to admit more refugees directly from Turkey. EU member states would make voluntary offers of the number they are willing to resettle.

Problem: Governments face voters hostile to immigration.

5. VISA LIBERALIZATION

Turkey to fulfill remaining requirements - about half of 72 criteria - by the end of April so the EU executive can recommend EU states to waive visas for Turks on brief trips by the end of June.

Problems:

- Many governments, notably France, do not want Turks coming to Europe without visas, partly on security grounds, partly due to popular fears it would mean more immigration - though only the few with modern, biometric passports would be eligible.

- Among the EU criteria are that Cypriots be treated like other EU citizens, something Turkey rejects since it does not recognize Cyprus as a state. Ankara has raised expectations at home of visa-free travel, making this a tough issue to crack.

6. AID FOR REFUGEES

EU ready to double its aid for Syrian refugees in Turkey to 6 billion euros up to the end of 2018.

Problem: EU governments are arguing about where the money comes from and whether it is premature to promise without seeing that Turkey is delivering on agreements first made in November.

7. FASTER EU MEMBERSHIP TALKS

“The EU, together with Turkey, will prepare for the decision on the opening of new chapters in the accession negotiations as soon as possible.”

Problem: Many EU states see little or no prospect of Turkey joining in the foreseeable future. Cyprus has vetoed opening several “chapters” in a dispute relating to Ankara’s refusal to recognize Cypriot statehood. The draft wording is conditional and vague enough for Nicosia, but will Turkey accept it?

8. SYRIA SAFE AREAS

EU ready to help Turkey help Syrians be better off and safer within their own country.

Problem: EU has no military clout and member states which do are wary of Turkey’s proposal of “safe areas” in northern Syria.