Brent crude oil crept above $50 a barrel on Thursday ahead of an expected decision by the European Central Bank (ECB) to start buying bonds, a move that could push the dollar to new highs and put downward pressure on commodities. Analysts said it was unlikely that the more than 2 percent rally was related to the ECB’s proposed monetary easing program. “It would be hard to relate this to the ECB decision today,” aid Harry Tchilinguirian, an oil analyst at BNP Paribas in London.