TUNIS, April 29 (Reuters) - French engineering group Alstom (ALSO.PA: Quote, Profile, Research) could still buy into nuclear energy group Areva (CEPFi.PA: Quote, Profile, Research) if the government decides to reduce its stake in the state-owned nuclear energy group, a French source close to the discussions said during a visit to Tunisia by French President Nicolas Sarkozy.

France is considering a number of possibilities for Areva's capital requirements, including full privatization, financial investors and industry investors.

The source said it was "a bit premature" to say that Alstom was out of the picture.

Alstom is headed by Patrick Kron, who has not made a secret of his interest in a tie-up with Areva.

Sarkozy, when finance minister, helped Alstom stave off bankruptcy when he arranged a financial bail-out with temporary state backing. Last year, the state sold its stake in Alstom to construction company Bouygues (BOUY.PA: Quote, Profile, Research), which increased its holding to 30 percent. Martin Bouygues is a close friend of Sarkozy.

Alstom makes non-nuclear parts for nuclear power stations, and is a leading manufacturer of high-speed trains and urban transport systems.

Germany's Siemens (SIEGn.DE: Quote, Profile, Research) has a stake in an Areva subsidiary and has said it has no intention of giving that up.

Siemens and Alstom are rivals, and Kron is still angry over the German company's attempt to get the French government to abandon Alstom during its crisis in 2003/04 so that its assets could be bought cheaply.

In 2004, Alstom was forced to sell its most profitable division, power transmission, to Areva. (Reporting by Emmanuel Jarry, writing by Marcel Michelson, Editing by Toni Reinhold)