- UK stocks opened modestly lower on Monday as the UK prepared to start offering Covid-19 vaccines to over-70s, while political tensions remained high in the US ahead of Joe Biden's inauguration on Wednesday.

At 0817, the benchmark FTSE 100 index was down 7.73 points, or 0.1%, at 6,727.98.

Device testing and analytics group Spirent Communications shed 0.7% to 260.77p, even as its annual revenue rose 4%, helping it to achieve a 'strong' rise in earnings in line with its expectations.

Spirent Communications said it may return excess cash to shareholders, but warned that an ongoing Covid-19 impact on customer spending patterns meant growth in 2021 was expected to be second-half weighted.

Pharmaceutical giants AstraZeneca gained 0.3% to £76.15 on news that it and Daiichi Sankyo had received US approval for their gastric cancer drug.

British gas parent company Centrica fell 2.1% to 49.57p, having announced departure of chief financial officer Johnathan Ford for personal reasons.

Ford was being replaced by Kate Ringrose, who has had been with Centrica for 16 years and most recently was its financial controller.

Healthcare company investor PureTech Health edged back 0.2% to 380.6p as founded entity and liver cancer focused Vor Biopharma filed a registration statement related to a proposed initial public offering in the US.

The number of shares to be offered and the price range for the offering had not yet been determined.

Animal genetics company Genus firmed 3.2% to £44.4893 after it upgraded its guidance on adjusted profit and revenue for the first half of the year, citing a continued strong performance.

Genus's adjusted pre-tax for the six months through December was now expected to be within a range of £47.0 million and £49.0 million, up from £36.6 million a year earlier.

Cosmetics group Warpaint London rallied 7.1% to 90p as it, too, upgraded its annual guidance on the back of stronger-than-expected trading in the second half of 2020.

Warpaint London's adjusted profit from operations, including a foreign exchange charge,would exceed £2.2 million, 10% ahead of previously stated guidance of £2 million, on revenue of at least £40 million.

Real estate investment trust LXi REIT added 1.4% to 117.62p, having lifted its quarterly dividend guidance after reporting 'robust' rent collection for the first quarter to date.

LXi REIT's dividend target had increased to to 1.46p per share for the quarter ending 31 March, up from 1.44p.

Alternative fuel group Velocys tumbled 27% to 7.51p on announcing that Shell had withdrawn from a joint venture formed to develop sustainable aviation fuel.

Velocys said it would continued to work with British Airways, the other partner in the Altalto joint venture, to secure finance for the Altalto Immingham plant.

Financial product and services company CPP jumped 20% to 392p after it upgraded its core earnings guidance following a stronger-than-expected recovery in India.

CPP's earnings before interest, taxes, depreciation and amortisation for the year through December were expected in a range of £7.1 million to £7.3 million -- 10% ahead of the market consensus of £6.4 million. Story provided by