The list of new names for Syria will become public today and while full details were not immediately available, a western diplomatic source confirmed that Syrian state oil company, the General Petroleum Corporation (GPC) would be among those targeted.
Diplomats said oil majors such as Royal Dutch Shell and France's Total could see their Syrian ventures grind to a halt as GPC joins the roster of sanctioned companies.
"These new measures are related to the energy, financial, banking and trade sectors and include the listing of additional individuals and entities that are involved in the violence or directly supporting the regime," EU foreign ministers said in a statement.
They added 12 people and 11 institutions and firms to an asset freeze and travel ban list, and prohibited financial support for trade and loans to the Syrian government, both bilateral and through international financial institutions.
The new measures prohibit EU firms from trading in Syrian state debt and ban banks from Syria from opening branches in EU countries or investing in European banks.
They also ban the export of equipment for the Syrian oil and gas industry, including refining and exploration, and investment by EU companies in firms constructing new power plants in Syria.
The sanctions also ban sales of software or equipment that can be used for Internet or telecommunications surveillance and the EU statement called for "restraint" on shorter-term trade support.
EU countries have imposed several rounds of sanctions against the government of President Bashar al-Assad Assad since May over its violent suppression of unrest, including an embargo on Syrian oil and a ban on new investment in the energy sector.
The EU statement said the bloc would continue to press for strong U.N. action on Syria and urged all U.N. Security Council members "to uphold their responsibilities to end the violence in Syria and support the Syrian people".
Russia and China, which both have oil concessions in Syria, teamed up last month to veto a Western-backed Security Council resolution condemning Assad's government for violence.
New sanctions on Iran
The EU also added 180 people and entities to its Iran sanctions list and laid out plans for a possible embargo of Iranian oil in response to mounting concerns over the OPEC producer's nuclear programme.
Sanctions have had an impact on Iran's economy, experts say, but they have not achieved their aim of stopping work that the West suspects is aimed at developing nuclear weapons. Tehran insists its nuclear activities are peaceful.
Last week, the United States, Britain and Canada announced sweeping new sanctions on Iran's energy and financial sectors.
Britain's move led to a vote in the Iranian parliament to downgrade ties and angered Iranian protesters, who stormed its Tehran embassy, causing Britain to close the embassy and to expel all Iranian diplomats from Britain.
Iran, OPEC's number two oil producer, exports 2.6 million barrels a day, and the state depends heavily on oil revenues.
But by disrupting the supply of oil from Iran, Western countries risk driving up the global oil price, hurting Europe as it struggles with a debt crisis. Greece is wary of an EU embargo because financial woes have led it to buy more Iranian crude.