LUXEMBOURG (Reuters) - Luxembourg's government and its finance minister face twin votes of no-confidence in parliament on Thursday over claims that the minister pressured investigators to close an inquiry into a rash of bombings in the Grand Duchy in the mid-1980s.

The governing coalition led by Finance Minister Luc Frieden's centre-right Christian Social People's Party (CSV) was expected to survive the vote. However, the outcome of the vote on the minister himself seemed less sure.

The votes relate to a series of about 20 bombings from 1984 to 1986 that damaged a number of buildings and injured one person. No one was killed.

Two former members of a special police force went on trial at the start of this year over the bombings. The motives for the bombings remain unclear.

Luxembourg's chief prosecutor Robert Biever has said that Frieden had repeatedly asked during his term as justice minister from 1998 to 2009 when the investigation would end.

This had left Biever and others involved in the inquiry with a sense that they were being pressured to end their probe, the chief prosecutor said.

Frieden denies having intentionally applied any pressure, saying he had just been concerned about possible delays to other important cases.

Wealthy Luxembourg, a major financial hub, is one of Europe's most politically stable countries. The CSV has led all but one government since World War Two.

Headed by veteran Prime Minister Jean-Claude Juncker, the CSV and its Socialist coalition partner currently hold 39 of the 60 seats in parliament.

(Reporting By Michele Sinner; writing by Philip Blenkinsop, editing by Gareth Jones)