July 29 (Reuters) - Spanish pharmaceutical group PharmaMar said on Thursday its net profit fell 62% in the first half from the same period last year, when it had booked a large upfront licence payment.

The company, which develops anti-tumour drugs from sea products, said its sales rose 24% to 65.0 million euros ($77.27 million) over the period, boosted by demand for cancer drugs.

However, its net profit shrank to 43.2 million euros from a year earlier, helped by an advance 181 million euro payment received from Jazz Pharmaceuticals under a licence deal in the first quarter of 2020.

The company's oncology division grew 33% in the January-June period to 62.5 million euros, boosted by European sales of a small-cell lung cancer drug Zepzelca, as well as stable performance of Yondelis, a drug to treat soft-tissue sarcoma and ovarian cancer.

Sales in the group's diagnostics business continued to falter due to lower demand and falling prices for COVID-19 tests, due the rollout of vaccination campaigns and stockpiling at health centres.

PharmaMar's R&D spending increased by 19.2% to 28.9 million euros in the first half, including 5.5 million euros of costs incurred in clinical trials to develop plitidepsin (Aplidin) for the treatment of COVID-19, the company said.

The group said in May that Aplidin, a drug originally developed to treat cancer, had shown clinical effects and met safety standards during early trials on hospitalised patients with moderate COVID-19.

($1 = 0.8413 euros) (Reporting by Anita Kobylinska; Editing by Jane Merriman and Nick Macfie)