The EU's six eastern partners hold diverse challenges (dpa German Press Agency)

Riga (dpa) – The European Union’s Eastern Partnership programme encompasses six former Soviet states, which have all been offered the prospect of closer political and economic ties to the bloc.

The six partner countries are as follows:

ARMENIA is the smallest Eastern Partnership state, with a population of 3 million. It came close to signing a political and free trade deal with the EU in 2013, but surprised Brussels by instead joining the Russian-founded Eurasian Economic Union (EEU), whose other members are Belarus and Kazakhstan.

EU officials have said the move is not compatible with concluding a free trade deal with the bloc, but another type of agreement is being developed.

AZERBAIJAN is a Muslim-majority country, rich in oil and natural gas. Its Shah Deniz natural gas field is the world’s largest and supplies energy to Europe.

But Baku has been accused of having a poor record on democracy and human rights. Campaign group Human Rights Watch urged EU leaders to use the opportunity of the Riga summit to insist that Baku must release all political prisoners, including journalists and activists.

The country is not pursuing EU integration, but has not joined the EEU either.

BELARUS is often referred to as the last dictatorship in Europe, and relations with Brussels are strained over its political prisoners and concerns about human rights abuses. However, Minsk’s role in helping to broker a peace deal for the conflict in eastern Ukraine may open the prospect of a future thaw in relations.

Pro-EU GEORGIA is one of three eastern partners to have signed a political and free trade deal with the EU last year, and would like to be considered for membership of the bloc. Georgia, as well as Ukraine, is hoping to be granted visa-free travel to the EU next year, but more work is needed to meet technical benchmarks.

The country has two pro-Russian breakaway regions, Abkhazia and South Ossetia, which were at the centre of a brief war with Russia in 2008.

MOLDOVA is one of the Europe’s poorest countries, with a gross domestic product of 1,700 euros (1,900 dollars) per person in 2013, compared with an Eastern Partnership average of 3,700 euros. However it is the only one of the six partners to have been granted visa-free travel to the EU. Chisinau has a pro-EU government and last year signed up to closer political and economic EU ties.

Moldova has strong economic ties to Russia, but relations with Moscow are strained due to the breakaway Moldovan region of Transistria, where Russian troops are stationed.

UKRAINE is by far the largest Eastern Partnership country, with a population of 45.2 million. The country is struggling with a pro-Russian insurgency in the east, as well as an embattled economy, which is expected to shrink by 7.5 per cent this year.

Ukraine has embarked on a path towards closer EU ties and committed itself to extensive political, economic and judicial reforms. But implementation is tough, given the country’s other challenges, which include entrenched corruption.

Ukraine signed a political and free trade agreement with the EU last year, but full implementation of the trade section was postponed until the start of 2016, to address Russian concerns.

The EU has unilaterally lifted its trade restrictions on Ukraine, to help the economy, and has also offered Kiev financial aid totalling 11 billion euros to support the reform process.