Istanbul (AFP) - Russia agreed Monday to lift some trade sanctions against Turkey imposed in the wake of the shooting down of a Russian warplane over the Turkish-Syrian border in 2015 but kept in place a contentious ban on tomatoes.

An accord on the lifting of the sanctions was signed on the sidelines of a summit of Black Sea regional leaders in Istanbul by Turkish Deputy Prime Minister Mehmet Simsek and his Russian counterpart Arkady Dvorkovich.

The Russian government in a statement confirmed that the document "on the lifting of bilateral trade restrictions" was signed in the presence of Turkish Prime Minister Binali Yildirim and Russian Premier Dmitry Medvedev.

Yildirim said remaining sanctions in sectors like construction, consultancy, tourism and wood would be lifted this month.

Meanwhile, the Russian import ban would end in a week on Turkish exports of fresh products like apples, pears, strawberries, cucumbers and poultry, he added.

But he acknowledged the import to Russia of tomatoes, a key Turkish agricultural export, was staying in place for now. Before the embargo, Turkey had supplied around a half of the tomatoes consumed in Russia.

"We have secured serious developments on all issues outside of tomatoes. We have shared our sensitivities on the tomato issue," Yildirim said.

Admitting the tomato had now become a "symbol", he added: "Regarding the tomato, we need more time."

Russia is keen to promote its own production of tomatoes as its seeks to diversify its hydrocarbon-based economy and develop agriculture.

Quoted by Russian media, Medvedev said that the ban on Turkish tomato imports would stay in place, although all other restrictions on fruit and vegetable imports had been lifted.

He said tomatoes were not included as Russia wanted to "preserve investments made in the sector that should not come to nothing."

The November 24, 2015 shooting down of the Russian plane led to an unprecedented crisis in ties and prompted Russia to impose a raft of sanctions against Ankara.

These included an effective ban on Russian package holidays to Turkey, ruining the 2016 tourism season in the country's south. That ban has since been lifted.

After a reconciliation deal last year, relations have seen a rapid improvement with the two sides working together in a bid to end the Syria conflict.

Erdogan had invited President Vladimir Putin to the Istanbul Black Sea summit, during a visit to Russia earlier this month. But the Russian strongman did not attend, with Medvedev representing Moscow.