* EU prepares ban on investment in Syrian oil industry
* International sanctions on Assad's government building up
BRUSSELS, Sept 9 (Reuters) - The European Union has moved closer to banning investment in Syria's oil industry as it pushes to raise economic pressure on President Bashar al-Assad and his government, EU diplomats said on Friday.
Envoys from the EU's 27 capitals have given preliminary agreement for a ban, which would constitute an important step towards hitting Assad's finances and complement the EU's embargo on crude imports from Syria, which took effect last week.
Pending final approval, the investment ban could be put in place in the coming days or weeks.
Europe's new round of sanctions against Syria may also include a ban on Europeans doing business with several firms, such as the country's largest mobile phone company, Syriatel, which provide funds to Assad, the diplomats said.
But talks on the issue were not finished yet.
"The investment ban has been agreed and there is another package of ideas being discussed," one EU diplomat said, speaking on condition of anonymity.
"But there is no decision yet on those and it is unclear whether there will be a push to finalise all measures together or in separate steps," the diplomat added.
Western powers are hoping economic sanctions will force Assad to end a six-month violent crackdown against anti-government protesters and relinquish power.
On Friday, Syrian forces arrested dozens of people in house-to-house raids in the city of Homs following military operations that killed at least 27 civilians on Wednesday. A grassroots activists group says more than 3,000 civilians have been killed in the Syrian uprising.
Europe has taken a slower approach to sanctions than the United States, largely because of concern in some EU capitals about risks to commercial interests of European companies.
The United States has an embargo on crude imports and a ban on investment in Syria, as well as a freeze on all Syrian assets in the United States.
The EU has been the biggest buyer of Syrian crude and several European companies, such as Anglo-Dutch Royal Dutch Shell (RDSa.L) and France's Total have significant investments there.
European governments have also been concerned that opposition from Russia and China to U.N. sanctions would blunt the impact of international pressure if it allowed Syria's business links to shift from Europe elsewhere.
Russian President Dmitry Medvedev has signalled that Moscow was ready to discuss a possible U.N. Security Council resolution on Syria, if it targeted the government as well as opposition for censure. . (Additional reporting by David Brunnstrom; Editing by Rex Merrifield)