Europe cautious as Greece and Fed watched

European equities are expected to open lower on Tuesday as the Eurogroup is expected to mull Greece's revised list of reform proposals. Investors are also cautious ahead of U.S. Federal Reserve Chair Janet Yellen's testimony before Congress over the next two days.

The FTSE is seen opening down 7 points at 6,905, the German DAX down 14 points at 11,116 and the French CAC down 5 points at 4,857.

The testimony from Federal Reserve Chair Yellen to the U.S. congress on Tuesday and Wednesday may give markets a better indication on when the central bank will raise interest rates. Yellen will be addressing the Senate Banking, Housing and Urban Affairs Committee at 10 a.m. ET on Tuesday and the House Financial Services Committee on Wednesday.

Meanwhile in Europe, investors remain focused on Greece after the country delayed sending its economic reform plans to the euro zone until Tuesday. The original deadline was Monday, but the Eurogroup of finance ministers agreed to the later submission of the reforms, Reuters reported. The plan is expected to include measures to crack down on tax evasion and corruption.

Greece's left-wing government led by Prime Minister Alexis Tspiras was given a lifeline Friday when the Eurogroup agreed to extend the Greek bailout by four months. The financial lifeline depends on Greece's presentation of new reform measures, however.

In Ukraine, the government accused pro-Russian rebels of opening fire with rockets and artillery at villages in southeastern Ukraine on Monday, Reuters reported, dashing hopes that a ceasefire agreed last weekend would take effect.

In commodity news, members of Organization of Petroleum-Exporting Countries (OPEC) have discussed holding an emergency meeting if crude continues to slide, Nigeria's oil minister told the Financial Times Monday, signalling that the 12 major oil exporter group is increasingly concerned over the lower oil price – Brent crude is currently trading at $58.90 a barrel.

Miner BHP Billiton reported a 31 percent drop in half-year profit Monday evening and other earnings are due from Persimmon, Valeant, Aer Lingus and Ferrovial on Tuesday. On the data front, German final fourth quarter gross domestic product (GDP) is due at 7a.m. GMT